Yes, unsolicited videos START the recruiting process for a large number of players. Do they finish the process? Not even close or at least none that I know of. Many advise to have subject lines that stand out or you risk never having the email even opened. Others swear to keep it simple. My son's email subject lines started out as "Joe Blow - 2021 MIF/OF {high school w/city]" and only crickets were chirping. We started looking at his PBR measureables and realized all of his were in the top 10 of the state for his class, so he tried the subject line "2021 MIF/OF with Top 10 [state abbreviation] Measurables - Joe Blow" and all of a sudden responses started coming back. Everything changed. The coaches were opening his emails, reading them and watching the videos they pointed them to. Relationships grew from there.
Are coaches getting inundated with ungodly numbers of emails 7 days a week? Without question. Even more so with Covid. I've seen some college coaches interviewed by Josh Rudd that say they don't want catchy subject lines. They want basic/less. That baffles me when I look at my son's experience. YMMV but I can't imagine getting any coach's attention with emails without something to draw them in. "You're a 2021 MIF/OF? Yeah, so is everyone else. [delete]."
If there are D1 coaches getting less than 100 unsolicited emails EVERY DAY from prospective players, I'd be shocked. Coaches at Vandy and Arkansas? Where's my calculator...