But since vq is not a documented parameter, https://developers.google.com/youtube/player_parameters, hard to say if it’s supposed to work or not. YouTube might be sensing the size of the player and sending the resolution that most closely matches by default. Kind of silly to send a 720p video to a 640×360 player as there’s not enough pixels to show the higher resolution.

Anyway, I tried various things I found on the net and none of them worked.