for a mac of course... tried using that split and concat app but it does not work.

MPEG Streamclip.

DVD2OneX has a nice "join multiple titles" feature that might work for you, if you're talking ripped dvds, that is:

http://homepage.mac.com/michaelmalone/Joining%20TV%20Episodes%20Together%20Using%20DVD2OneX%20and% 20Mac%20the%20Ripper.htm

Mpegstreamclip converts the 5.1 audio to 2 channel. Unless they fixed this in the last 2 years I highly DO NOT recommend this app for combining TS files.

I use hdtv2mpeg (I think, it's a java app but not at my Mac right now to confirm).

i dont see a mac version of hdtv2mpeg

Look for NullPacketStripper.

ok im bringing this back. because either nullpacket isnt working anymore or im doing it wrong.

if it matters the files are named with only three digits. dfsdfs.003.ts

its only processing one file.

Try D-Vision (http://www.objectifmac.com/dvision.php), it always works and has some very nice other features as well.

How do you merge .TS files... it only allows me to select .avi files

Sorry about that. However, there are two other possibilities still. One is called Ajoiner. Be sure to read the instructions because you must number the files a certain way. The other is called ffmpegX. Once you set this up, you will see a tab called "Tools". Once you select Tools, you will see another tab that says "join". It lets you select two files and should combine them. Both of these programs are free and you can find them at Versiontracker.

Unfortunately, I don't have any .ts files, so I can't try them myself. Good luck.