I just checked the HD version of the Apple TV ads on their main page right now. They’re 848×480 in resolution and also H.264 with AAC audio.
As for your “bulkiness” problem you have two things working against you. First is that the ad and the movie trailers are all 24 fps. I’m assuming your HDV footage is 30 fps. So even with all the same settings and same length, your video’s file size will be 125% the size of the movie trailers.
Secondly, everything on there was shot on film or very hi-rez digital format. They also used huge professional lenses. That means their footage is way sharper and way larger than what you’re starting with. That means they can compress it at a VERY high rate and still get good results. Everything’s so sharp and they’re starting with so many pixels they can really run it through the ringer and still get a good image.
You’re starting out with just barely enough pixels to make what you want. Any compression that looks great for them will probably do more damage to your video. So you’ll need a higher bit-rate to match their look.
So you’ll have to compress less than they do AND you have more frames-per-second. You can see the problem.
But don’t give up! With a bit of trial and error I’m sure you’ll get something that looks great. I’ve gotten some great results with just DV footage. Take a look:
http://www.penguintail.com/parrot/
A lot of this stuff is trial-and-error. Just keep trying different things and you’ll find something you like!