MJPEG 4:2:2 chroma recording/playback issue
**Describe the bug**
A recorded video from a MJPEG camera source (i.e. ESP32-CAM/TTGO T-CAMERA/...) fails to play in common browsers.
Firefox error message: "No video with supported format and MIME type found.

If I re-encode the recorded mp4 file with the following command, the video can be played without any issues.

`ffmpeg -i source_file.mp4 -pix_fmt yuv420p -b:v 4000k -c:v libx264 destination_file.mp4`

H264 videos expect a 4:4:4 chroma sampling which most MJPEG cameras don't support.

No issues with live videos from the same source.


**To Reproduce**
Record a video from a MJPEG camera source.
Playback the video through the camera-ui.

**Expected behavior**
Video should play in common browsers without issues.


**Screenshots**
![Screenshot 2021-11-17 at 10 55 59](https://user-images.githubusercontent.com/1226390/142182102-ada7f48b-25d6-4165-bb62-fcd342916e32.png)



**Environment**
- Node.js Version: v14.18.1
- Homebridge Version: v1.3.6
- Camera UI Version: v4.2.10
- Operating System: raspberry debian buster
- Browser: Firefox Max 93.0 (64 bit)
