I think it's really useful to describe your product as an alternative to a well known product. Most people will instantly get it, much more so than a long re-definition of the original product.
The target customer is a business who is making demo videos and needs these kinds of tracking/collaboration/commenting features.
Folks interested in open source maybe want a better offering, don’t want to be locked in, want more favorable pricing, or want a self hosted version.
As someone who has used loom, the value proposition is clear from the title without even going to the website.