Think about the last online course you paid for and didn't finish. You probably weren't disappointed by it. You watched a couple of trainings, thought it was good, meant to come back on the Tuesday, and then a week passed and the tab was closed and that was that.
That is what is happening to your students right now, and it is almost never a content problem. Someone joins on a Thursday with real intent, and intent has a half-life of about two days. Someone finishes their first training feeling good and has no specific reason to open it again tonight rather than next week. Someone hits the training that requires actual work and postpones it once, which is usually forever.
None of those three moments can be fixed by recording a better video. They're fixed by something noticing — and by a message that names the exact next step rather than asking how you're getting on.