Videos in Rise

HI - how do videos work in Rise? Is there any sort of pre-loading, like in Storyline, based on which lesson it's in? Do videos progressively download so they start playing before they have downlaoded? I have some quite large vids embedded and the whole course is taking a long time to load, even the cover page. This is through an LMS - seems OK when I preview in Rise. I know I can put them on Vimeo or Youtube and embed but this sometimes causes problems with client firewalls etc so would prefer to keep them wihtin the SCORM but can wait up to 30-40 seconds for the course to load.  Doens;t seem to be any infi on Rise video in the product help

thanks