I have a webseries from YouTube that I've downloaded and added to the Channels library, and set up virtual channels. One season will only play audio but no video. I checked the files and that season is using the VP9 video codec and the others are using AVC. Does Channels not support VP9? I can convert them to .265 if needed but some early conversions resulted in files more than twice the size of the original.
Try the beta app on your FireTV
Or try changing Settings > Playback > Advanced > Video Decoder to Software
Changing the decoder to Software fixed it, but buggers up other channels. I have to switch it back to Hardware all other times.
How do you use a beta app on the FireTV?
Edit: nm, I found it.