see hd movies apple tv2

Yes it's perfectly feasible.

I assume you've set up Home Sharing on AppleTV and in iTunes on Mac.

Any compatible iTunes store purchases appear on AppleTV under the Computers column which loists available itunes libraries on the network - do you see the iTunes library there. Movies will be in that libraries Movies row, rentals made through itunes on the Mac appear in a new Rentals column here not under the main AppleTv Movies category. Mac must be on with iTunes running for AppleTV to see the movie.

Some things for bizarre licensing reasons are only avaialble in HD on AppleTV or iPad - you may find only SD versions in itunes on the computer.

In the future iCloud may allow all manner of purchased content to be seen streamed directly from the internet on AppleTV rather than from a local itunes library but this only applies to some content currently and is US only so I can't try it.

AC

Welcome to the Apple Community.

I want to buy a HD movie in iTunes store and see it on my HD TV through Apple TV2, is that possible?

I don't think that's possible if you mean purchasing it via the Apple TV 2, AFAIK currently only TV shows can be purchased via the Apple TV, movies would have to be purchased on your mac and shared as suggested by Alley Cat.

Last week I rented a HD movie in iTunes store and I could only see it on my Mac

If you rented it from your mac, you would need to let it download completely before your Aple TV would see it.