Using a video sales letter or a webinar, what's the best way to track how much of that video someone has seen to know if they actually reached the point where they heard the pitch?

<p>I just had a quick question about using a video sales letter or webinar. Let's say I put it on my thank you page for my lead magnet, so someone comes in, they opt in. They go to the thank you page and then I want to give them some trainings with a pitch that follows in video form.</p> <p>What's the best way to track how much of that video someone has seen to know if they actually reached the point where they heard the pitch?</p> <p>Depends on what you're using...</p>