@Mubsi @Deepti_Prasad while you’re at it, can you also validate that short course videos don’t play on Firefox?
After clicking play in https://learn.deeplearning.ai/courses/multimodal-rag-chat-with-videos/lesson/1/introduction the circle spinner appears and never ends.
Here is the screenshot on my system (Fedora 40):
Honestly I didn’t use Firefox for these courses learning.
So can’t much tell about this, all I know firefox has more privacy settings than compare to other browser, so probably that is the reason it is not allowing you to load the videos.
I found a trouble shooting link with firefox, go through it point by point, to link what could be your issue, I am suspecting either antivirus installed or proxy settling comes with an website not allowed by Firefox.
hope the below helps 
Regards
DP
That doesn’t help.
I’d appreciate if somebody from testing team could install latest Firefox and confirm that videos don’t load there.
@Deepti_Prasad @Mubsi any status updates regarding Firefox support from the testing team?
Nope, the last I remember L.T mentioned to use either chrome or safari.
@Deepti_Prasad I don’t know who is L.T.
Support for multiple browsers makes application built using web standards, rather than on top of specific features of certain products.
Firefox accounts for 6.38% of tech savvy users (Desktop Browser Market Share Worldwide | Statcounter Global Stats), and supporting it is not hard if DLAI got its CI infrastructure in place. Polyfills and frameworks make it not tedious. Would be nice to read more about DLAI development.
Supporting Firefox gives an example of positive ecosystem collaboration. Mozilla maintains llamafila and embeds AI in the browser.
Mubsi is the learning technologist. ofcourse we are suppose to have all browser support programming but as far as I can understand sometimes these could have created issues with the dependencies and firewal settings comes with different browsers and hence it must have not been working.
kindly wait for @Mubsi response what he responds to this.
I’m using Firefox. I don’t have any problem watching the videos for this course.
Thanks for the info. I use Firefox 132.0.1 on Linux. Here is the JavaScript console. How to troubleshoot it further?
Firefox 132.0.1 on Windows 10.
I have no idea how to debug a browser. I have never had to.
hi @abitrolly
Open Firefox and navigate to Options in the top-right drop-down menu. Go to Privacy and Security from the menu bar on the left side. Click on Clear Data in the Cookies and Site Data section.
Also check cookies settings
Then try running the website again.
Cleared cookies, unchecked “Enhanced Tracking Protection”, even run it all in private window. No changes
Security Error: Content at https://learn.deeplearning.ai/courses/llms-as-operating-systems-agent-memory/lesson/1/introduction may not load data from https://dyckms5inbsqq.cloudfront.net/MemGPT/C1/L0/subtitle/eng/sc-MemGPT-C1-L0-eng.m3u8.
hi @abitrolly
See below images if you have done all this section
even I am able to run the course in Firefox browser. I ended up downloading firefox browser for your issue 
Hope this helps.
It seemed more like more of your privacy settings issue with your browser or system dependenceies which I am not sure I can find until I am using your system
Thanks for testing this out. The strange thing videos play for other courses like Finetuning Large Language Models - DeepLearning.AI, but not for LLMs as Operating Systems: Agent Memory - DeepLearning.AI
There is Sentry error in console that is not sent, because Sentry is out of quota, so I attach it here.
sentrylog.js (171.3 KB)
try uninstalling sentry from your system and then run? you can redownload sentry again.
The reason I more not able to understand as you are working on a different software and I checked Linux comes with sentry helping debugging codes, but what I am not able to understand why it is selective about only this course, and my suspicion is there might be some inbound filters or in your software or system setting not allowing some content of this course
I found that learn.deeplearning.ai uses GitHub - video-dev/hls.js: HLS.js is a JavaScript library that plays HLS in browsers with support for MSE. but so far no luck finding anything Firefox specific.
try uninstalling sentry from your system and then run? you can redownload sentry again.
https://sentry.io/ is a service that your development team uses to catch production errors with necessary debug info, and they don’t get my error, because the account is out of quota. This is the error response from their servers.
“Sentry dropped data due to a quota or internal rate limit being reached. This will not affect your application. See Billing Quota Management for more information.”
I also have no idea what is so specific about my PC. Maybe there are problems with configuration of CDN zone, or maybe these courses use different codec settings - logs don’t show anything. I will try it loading from USB flash using different Linux.
I gave that 171Kb Sentry log to some “secret-chatbot” LLM and it told me there are no server side problems.
The Sentry log doesn’t directly reveal why the video isn’t working. It shows a series of successful HTTP requests (status code 200), including requests related to fetching lesson data and even a request specifically for a video (
/api/trpc/...course.getLessonVideo...videoId%22%3A570). This suggests the backend is responding without errors, but doesn’t confirm the content of those responses is correct or that the video playback itself is working on the client-side.
So I concentrated on analyzing the video stream, and indeed, neither vlc nor ffmpeg can play it on my system. I attach archive with downloaded video files here.
sc-Intel.zip (6.2 MB)
Basically ffplay sc-Intel-C1-L000000.ts gives a ton of these messages.
[libopenh264 @ 0x7efefc2896c0] [OpenH264] this = 0x0x7efefc10cf80, Warning:ParseSps(): frame_mbs_only_flag (0) not supported.
[libopenh264 @ 0x7efefc2896c0] DecodeFrame failed
But identifies the video as h264.
Input #0, mpegts, from 'sc-Intel-C1-L000000.ts':
Duration: 00:00:11.26, start: 1.420289, bitrate: 5711 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100](eng): Audio: aac (libfdk_aac) ([15][0][0][0] / 0x000F), 44100 Hz, stereo, s16, 192 kb/s
Stream #0:1[0x101]: Video: h264 (libopenh264) (Main) ([27][0][0][0] / 0x001B), yuv420p(top first), 1920x1080, 29.97 fps, 29.97 tbr, 90k tbn
I have no idea what’s going on.
I do use Ubuntu and Firefox with out problems on seen videos, except for Amazon Prime that lately want more updates.
Cheers
Julia
A mystery to be solved 
@abitrolly
I was just wondering did you try to run all the slides of this course? or just the first one? try incognito also once.
it is always better to try various option when you are not finding a solution!