Some bugs with the new 'Minecart with TNT'

Hello !

I found a lot of bugs with the new 'Minecart with TNT'
At first, the TNT can make no damage sometimes.
I get a lot of weird explosions on the ground and all over the TNT, up to 50 blocs longer.
And sometimes it can also break obsidian ! I could break more than 20 obsidian blocs yesterday.
I create a video to show you all these bugs : http://www.youtube.com/watch?v=LvRC6yH-vuM

Thanks for your work.