I am doing some animations for use on a website. so that when someone rolls over a particular element it would play a 3secong video of a Jack popping out of his box.
The video will be uploaded to the server space specified for the website.
That is the best way/format to export this animation?
Are there thisng other than resolution to consider?
Use flash. Render an h.264 and use flash to embed the movie. Any media player is going to give you a player window.
To make it mobile compatible, set your comp's frame rate to something like 6 or 10, make the comp 2X the size of your roll over to accommodate high rez displays, export an animation codec QuickTime with an alpha channel, bring the movie into Photoshop and save an animated gif from the movie. Much easier implementation too. Just use the gif as a roll over image.