What affects SEO is the actual amount and quality of text that is on your page, not videos. If you're trying to rank for SEO, don't make a page that consists solely of a video with only one line of text.
Remember, the google crawler extracts paragraphs of text from the HTML it picks up on your website then uses that as a factor to determine where in search results your webpage appears.
I'm predicting it will take a long while as well as added expenses on google's end before they will go into scanning video content frame-by-frame to determine website content.
I would say that it depends on what you had to begin with. Like Mike said, your primary SEO ranking factors will come from your actual on-page content.
However, if your videos were marked up using structured data, they may have added some SEO value. Even if they were marked up and suddenly became enveloped in JS, it wouldn't play a big enough role to shake up your SEO rankings (unless you had a large amount, and your home page was primarily videos - in which case you wouldn't have much SEO value anyway).
My advice is not to worry about them being in JS. If you want to sustain/increase any SEO value in those videos, host them on YouTube and do some optimization there to increase their visibility. That could help you get some referral traffic or awareness.