I'm kind of new at this. I purchased a JVC HD camcorder that records in AVCHD mode.. MTS files.

So, I have Premiere CS4 and After Effects.

I recorded a concert and want to overlay the bands logo, song title, date and location of concert.

I can put on the logo and encode a song in Premiere for YouTube HD just fine.

If I bring that into After Effects and add a title then go to Composition -> Render it outputs an AVI file.

Is that the correct way to do things? I was just worried because I encoded with the YouTube HD setting and it gave me an mp4 file, yet After Effects gives me an AVI.

Not to mention that the AVI file is a lot larger than the mp4.

Why use AE?

Just create the title in premiere, and slap it on a higher track than your video, and it will super it over the top - you can add a fade in and out if you want - the render time won't be bad if it's just a few frames in various places - then render it out to avi using media encoder, and select the output format there.

I can't see why you need to get ae involved?

The correct way depends on what your output is going to be DVD, BD, web, media player or .....
AE can give you many formats but so can Premiere. If you do not want fancy stuff Premiere/AME is all you need.

Well, I explained in my original post the output method.. YouTube HD.

So, I've since used just Premiere. I was originally wanting After Effects for an animated title.

It was not clear if YT was your only output or if you had more.
If you want to use AE for a title that is ok, just DL it to Premiere or render it out to an uncompressed or Lagarith avi.
Export timeline in Premiere with YT preset or one of the HDTV presets.

Yeah only going to be used for YouTube.

Thanks for the clarification guys.

So, if I want fancy first I load unedited video into AE and add my title/effect.

Then do I go to Composition -> Make Movie and use lossless, or do I go to Export -> AVI.

No you do not load you unedited material in AE.
Just make the title and render it out with an alpha channel to get transparent background.
Always go through the Render Queue.