Watching your video leads me to think that the engine is turning way too hard. You should be able to put both hands on the flywheel screen and rotate the engine at least to the compression stroke. Until that can happen, I wouldn't think the starter would turn it. If you remove the two bolts and drop the starter down, it should spin easily and run with a jump from the battery. The starter bearing could be tight. Spark won't happen until you get the engine to spin.