there's an option in HTML5 to display a video file and a parameter in that case to keep it looping. Not all browsers support mp4 natively though. You will want to develop with a browser that does, and then add alternate formats for other browsers if you care for those too.

Search for 'html5 video tag' on google or similar,, such as

http://www.w3schools.com/html/html5_video.asp

That one will show you which main browsers support which formats, such as mpo4, ogg/ogv, and more

For image sequences: I have an image sequence displayed as slideshow at www.thebest3d.com/slideshow9.5 - look for the source in the html page then grab the javascript code referenced.

It's not the best and coolest but it works, and in this case the images are not all the same dimensions, but in your case they will, and you can change the code to play randomly but if for an image sequence keep them in order.

How many images in your clip sequence, and what dimensions?

Keep them as Jpeg, in general that will load faster, with a few rare exceptions. What file size per each image in your sequence?