Tor Browser can't play MP4 files


In my case the Tor Browser can’t play MP4 files. An example would be this site:


While the WebM file plays fine I get prompted to download the MP4 file because “Tor Browser cannot display this file”.

YouTube is working using HTML5.

I noticed that the Tor Browser doesn’t have the OpenH264 plugin maybe that is the reason?

For testing purposes I tried installing the OpenH264 plugin or getting it to download by setting “media.gmp-provider.enabled” to true in about:config but it would only say that the plugin will be installed shortly. I don’t remember the exact wording sorry.

Does someone else have this problem if it even is one?

Good day,

for security reasons, running certain file types inside the “Tor Browser Bundle” is deactivated. That’s the case here.

Have a nice day,


i think i was having the same problem , the default TBB from torproject which is whonix is using = u cant watch every website and one famous website for e.g is vimeo

while inside Tails , they make some modifications to the TBB = so u have more opportunity to open more video types/forms inside the websites for e.g vimeo


Thank you for replying.

Is there a way to deactivate what is restricting the Tor Browser from playing MP4 files?

Would it make a difference if I manually downloaded the Tor Browser Bundle directly from the Tor Project’s website?

Also how harmful to your anonymity would it be to deactivate the security feature if it can be deactivated?

Good day,

Yes, by enabling:


in “about:config”.

No, the TBB isn’t modified for Whonix.

Very, fingerprinting you will be very easy and unavoidable. Furthermore, this can lead to a multitude of security issues, which could be used by an attacker.

Have a nice day,


Some more and less related references.


I wanted to try this but I couldn’t find it in about:config.

Thank you for your time and help.

Good day,

just type it in the search bar. Though like I’ve said, this can cause massive security and anonymity issues.

Have a nice day,


Hello again.

I did but no results.

But it couldn’t lead to deanonymization right? I would of course only enable these options when absolutely needed.

Good day,

first of all, en- and deenabling featuers like this will not really benefit you, as your fingerprint is even easier to “pin point” when you make it a habit to fluctuate the configuration in a predictable way. It might actually make it (even) easier to track you, then keeping the feature enabled all the time. Furthermore, what issue are you currently facing then?

Have a nice day,


Thank you for replying so fast.

I understand. What if I made two different workstations one has the feature enabled and the other disabled and I only use the one that has it enabled to browse websites that need it. One of those websites would be Vimeo as far as I know.

Also using the search function in about:config to search for the features I need to enable doesn’t bring up any results.

Good day,

sorry to say, I was mistaken about the compatibility. As I just found out, full support to running .mp4 inside FF (and thus also the TBB) is limited to Windows, because of licensing, see here: https://developer.mozilla.org/en-US/docs/Web/HTML/Supported_media_formats That’s one of the problems with “cross platform apps” what is possible on one OS may not be possible on another OS.

I’d recommend using VLC at this point anyway though: http://superuser.com/a/782685

Have a nice day,


For me, the hardest part of troubleshooting is figuring out whether something is a Qubes / Xen / Whonix / Debian / KDE / VirtualBox / Tor / Tor Browser / Firefox issue! Ego did the hard part, easy part - search “play mp4 iceweasel”.

Tested, confirmed working in ICEWEASEL in whonix-workstation:
I could not get it to work in Tor Browser. You could open the 2 side-by-side and go through each about:config option - but no guarantee that would work either.

WARNING: Iceweasel is unmodified by Whonix, meaning you have to harden it yourself and configure privacy settings / addons yourself. You may just want to use with default settings + workaround in link to reduce fingerprint? In this case, definitely use a dedicated + disposable/amnesic VM for this purpose. IP will not be de-anonymized - thanks to Whonix - but should assume you will be pseudonymous (unique fingerprint).

Safest to download videos with TBB as Ego said, then play on un-networked disposable VM.


Not a problem Ego. I figured that this might only be available on Windows because of the “windows-media” part.

Thank you entr0py I will take a look at this.

Sorry man, it seems that you know quite a lot about video playback issue. I have a question about it and would you mind me asking here? The thing is that recently I downloaded a YouTube MP4 video at this site as you can see " http://www.videoconverterfactory.com/tips/vdgb-yt-downloader.html"(I hope someone else if at convenience can check it), the videograbby. I move the MP4 video to my Windows Media Player. However, to my disappointment, there was only video output no audio, but after I converted the video to regular AVI video, then it was okay. why did this shit happen? Was that because of t he downloader itself or any codec errors?

I also face this problem.For some reason, YouTube downloads in MP3 and the TOR browser can not download tell me who faced such a problem.

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