From my reading newer editions of Adobe can read the .mts format, but notCS3. Since you are using CS3, I’m going to guess you don’t have a 64 bit system, if you do though, you could download a free copy of CS6 and just work with that though(trial basis)—though I can’t say with 100% surety that AVCHD will play in the trial mode.
Knowing that the format is .mts(not one I use, so I’m not very familiar) I did a google search for AVCHD.MTS convert and found some free shareware programs that you could try. You could do your own search or here is one you might TRY.
If you are just stringing together 5 clips, sure AE’s fine, but once you start to actually have to edit, you want to use an editing program and it’s a pain to edit in AE… it’s just not designed for editing.
Hope this helps out and good luck on your project…guess I was lucky, when I was a student we just had tape and it was always in one format—tape.
Johnny Cuevas, Editor
Thinkck.com
“I have not failed 700 times. I have succeeded in proving that those 700 ways will not work. When I have eliminated the ways that will not work, I will find the way that will work.”
—THOMAS EDISON on inventing the light bulb.