You're not reaching depth... not ideal and IMO puts more stress on the knees. This is anecdotal... I haven't searched for evidence to back this up, but everyone I know who 'half squats' complains of knee pain.
/BroScience
The one thing I noticed as the camera moved to the side view in the first video is that you have some knee slide. Sorry, I don't have much else based on the camera angles.. maybe someone else will be able to offer something more constructive.