best video compression for ePub3

Hi
I have been searching online but have not found any censuses on what is the best codec and compression settings for video to be used in ePub3.

Some say mp4 others m4v (as it is said that Apple won't accept any thing else, but it does not necessarily work for all Android devises) some say it needs to be under 1000Mbps others say it can be over.
Can it be 1080p or does it need to be smaller?

Also I have had no success with viewing imbedded video and audio in ePub3 for Android or PC.
Has anyone had success, which ePub3 readers do you use?

Can you point me in the right direction?

Thanks for your help, Ricky

Very interesting question. I'm going to ask around and see.