The reason why you should upload movies with the height of at least 485 is that it becomes a lot crispier and clearer.
A pokertable contains a lot of fine details which requires a certain resolution to be properly watched.
The best way to watch a pokergame on PokerTube is to click on the 360-bar and choose either 480p or 720p than enlarge the player to either 2x or fullscreen.
If you have uploaded a movie with less than 480p in height, the movie will only be encoded to 360p and the 480/720 option will not appear. If you choose to enlarge the player to 2x or fullscreen in this case, the movie will be enlarged but shown in a very poor quality.
To make a succesfull recording, see that your settings are set right through out the whole process, Recording, Saving, Exporting, Encoding and Uploading
Baggy