I build webpage by Hype and always need embed video into webpages, and export them as oam format and upload them into wordpress by Hype wordpress plugin.
The <video> tag will by default download a portion of the video, but only when the scene is loaded. Your .m4v video is actually the last item loaded on the page so it is not slowing down the load of your page:
Here’s a bit more info on how preloading works if you want to change the default using a custom Video tag:
In Hype, we don’t set a preload tag on videos loaded as a regular video element, so the browser does what it thinks is best. In Chrome, for example, by default the first few seconds of the video are downloaded so playback can occur quickly.