One way to grow your list with highly targeted people (which should be our main goal since anyone can grow a big list but if that list is not really targeted then that list might be wothless) is giving away valuable information in your niche so you start becoming the GO TO person.
You can have something like this (this is just an example):
free high value niche related video => capture page (the capture page could be at the middle or at the end of the video).
It might work better if you place the capture page about 5 or 6 minutes after the video starts and then ask then for their email in order to continue with the training but since they already tasted the type of high value training you are providing the conversion rates are higher than if you place the CP before the video starts or at the end.