Hey Moleman.. your rhythm playing is really great. You do need to work on palm muting though.. because this lesson is called Metal for Beginners, and palm muting is such a huge part of metal and a feature of Lian's lesson, I've had to give you a lower score.
Try experimenting with adding more pressure with the side of your hand (the shuto part, knife hand... it says you're from Tokyo so I'm hoping you know what I mean !
)
Using the side of our hand to rest onto the strings whilst playing gives us that 'chug, chug' sound...
Also, another thing that may help you with rhthym playing is this; you don't need to keep your little finger touching the body when playing riffs. If you normally keep your finger touching the body that's fine.. it's cool for alternate picking and smaller techniques.. but when you rock out and play things which require bigger movements, it's ok to lift your finger off and move your whole hand. It adds to the attitude and feel.. it won't hurt your alternate picking technique either.