Since you do have the video on roll tacking, you might want to review it again. It sounds like you are not turning the rudders hard enough. That and not releasing the mainsheet when head to wind. Both of these are major errors that will get you head to wind and stop.

Review: You must be sailing close-hauled with main tight. Start your turn with steadily increasing pressure on the helm (If you jam it over, it will stop the boat; if you steer to easily, you will blow off all your speed before you make it through the turn)

And with the mainsheet tight, you are using the tight leech of the main to weathervane your turn into the wind. You must then release the mainsheet a foot or two when you go through the eye of the wind. That eases the leech of the sail -- otherwise it will want to continue weathervaning directly into the wind. That also allows the mast to straighten, making the sail fuller -- this is akin to a race car driver shifting down into 2nd gear from high when going through a tight turn. By easing the main sheet, you are making the sail fuller and more powerful to come out of the turn.

Hope this helps. If not go watch the video some more.
Good luck,
Rick