I was watching the video and noticed a few issues with the siege towers. Firstly, to me, they seem to be moving way too fast. IMO they need to be at a more "crawling" pace. Is there any particular reason for their apparrent speed? They also seem a bit "jerky" in their movement.
Secondly, I don't see any troops in them, as they are moving. Like the elves' trees of war, I think they should maybe have a few archers up top, as well as some infantry to storm across as soon as the "bridge" is lowered.
The last issue I find with the siege towers is that there is nothing pushing/pulling/moving them. Are there supposedly men inside the lower section wheeling it along? This seems a ridiculous notion to me.
So, my idea of what siege towers should be like is slow, well-armoured beast of war that serve as both a path onto the enemy walls as well as a fighting platform. There should be plenty of time between when the first shots in a siege are fired, and when the siege towers make it to the walls.