Re: Ukemi problems
I like Chris Hein 's explanation and to that I would add don't reach to far forward with your right hand. The placing of your hand depends on your forward momentum, the slower you are moving the hand is placed closer to your foot.
I am assuming the second fall is a back fall in which both hands are placed on the mat and you flip over your head and arch your back while slapping with your arms and feet. The only suggestion I have for that is to tuck your chin to your chest use your arms to maintain a straight direction with out supporting your weight. Use your legs to project only your hips over your head.