To avoid the large number of compatibility warnings during export, you could change your Document Inspector to just have 'latest' selected:
For that config, you would be absolutely fine with just using a single MP4 video (encoded in h264). Here's current support for the Mp4/h264 codec: Can I use... Support tables for HTML5, CSS3, etc (It's great!). When Hype was released, browser video had not coalesced in a single video format, so for widest possible support we provide options for additional codecs.
When looping it plays a white flash, or when reloading the page? A poster image for your video might help:
https://forums.tumult.com/t/setting-background-or-poster-image-for-video-elements/6126/3
Some browsers put a X over the video element or a play button with a / through it. It depends...