There is an option to 'upgrade' your video to 1080p on Vimeo, but I am very curious what effect switching 'HD' on has if you don't upgrade your video. My understanding is that the HD switch always changed the resolution to 1080p. Am I wrong?
Also, is it necessary to upload a 1080p source video for Vimeo to 'upgrade' your video, or does Vimeo resample your 720p video up to 1080p?
A lot of confusion as to exactly what is happening behind the scenes when you upload to Vimeo or YouTube.