Description of problem:
BigBlueButton: sound + application/screen sharing + webcam do not work in Firefox 78 ESR installed from Mageia repository.

Version-Release number of selected component (if applicable): 

The problem is present in every Firefox 78 ESR installed from firefox-78.*.*-*.mga7.x86_64.rpm or firefox-78.*.*-*.mga8.x86_64.rpm
Everything works fine in Firefox 78 ESR installed from ftp.mozilla.org.
Everything works fine in Firefox 68 ESR installed from firefox-68.12.0-2.mga7.x86_64.rpm

How reproducible: Always (tested on 2 machines: one with Mageia 8, the other one with Mageia 7)

Steps to Reproduce:
1. install firefox-78.*.mga7/8.x86_64.rpm
2. https://test.bigbluebutton.org/
3. join the session with microfone
4. share an application window or the whole screen
5. share a webcam

Below, I include more information from testing on Optimus laptop:
- Intel Iris PLus Graphics G1 (Ice Lake) --> Intel 810 and later
- GP107M [GeForce MX350] --> NVIDIA GeForce 635 series and later
with mageia-prime installed (Mageia 8):

1. No sound in BBB when using:
- Intel graphics & Firefox ESR 78.x
- NVIDIA graphics & Firefox ESR 78.x

There is no sound while echo testing, in BBB sound settings I see
  ┌────
  │ No audiooutput found
  └────
Testing the speaker volume (clicking Play sound in BBB sound settings) produces audible sound.

The echo test passes when using:
- Intel graphics & Firefox ESR 68.12
- NVIDIA graphics & Firefox ESR 68.12


2. I cannot share an application window under the following configurations:
- Intel graphics & Firefox ESR 78.x
- NVIDIA graphics & Firefox ESR 78.x
- Intel graphics & Firefox ESR 68.12

The application is not shown when I choose it in "choose window or screen to share" windows. When the share button is clicked the application gets focus, but it is not shared.

Everything works properly when using:
- NVIDIA graphics & Firefox ESR 68.12


3. I cannot share the whole screen under the following configurations:
- Intel graphics & Firefox ESR 78.x
- NVIDIA graphics & Firefox ESR 78.x

In contrary to the previous situation, the screen is shown when I choose it in "choose window or screen to share" windows, but it is not shared when the share button is clicked.

Everything works properly when using:
- Intel graphics & Firefox ESR 68.12
- NVIDIA graphics & Firefox ESR 68.12


4. Share webcam option fails when using
- Intel graphics & Firefox ESR 78.x
- NVIDIA graphics & Firefox ESR 78.x

The following message is shown after about 5-10 seconds:
  ┌────
  │ Media could not reach the server (error 1020)
  └────

I can share my webcam when using:
- Intel graphics & Firefox ESR 68.12
- NVIDIA graphics & Firefox ESR 68.12