Okay-- so now I've got it to work HOWEVER...

There's a 1 second delay! And I can't seem to get the "Synchronization Delay Time" lower than 1 second?!!!

Anyone have any ideas?

No point in sync with a delay like this!

Here I have same LoopBe Internal setup, and is very good for MTC = very close but not sample-locked. Certainly no 1sec delay!

Things to try:
Are you using ASIO Drivers? (with ASIO audio drivers sync will be within quarter frame, with WDM/MME audio drivers you can add a frame to that, depending on your soundcard, due to latency)
Check there's no offset in your Host (Master) settings.
Vegas |Options|Preferences|MIDI > LoopBe is not set for MIDI output.
Vegas |Options|Preferences|Sync > Framerate is same as Host/Master.
Vegas |Options|Preferences|Sync > Advanced - Offset adjust = 0 .
(on that 'Advanced' page it's ok to have 'Synchronization delay' = 2sec, or even 1sec on a fast PC, as that is just the time for sync to be 'found')

Also, if you are using same audio file to check sync, make sure the samplerate setting of Vegas and Host/Master are set the same!

BTW, a bit late now, but I think I just found a bug in VegasPro10e / WinXPpro = if |Options|Timecode|'Trigger from MIDI Timecode' is enabled, selecting |Options|Preferences crashes Vegas. But VegasPro10e[32b or 64b] seems stable in Win7_64 in same circumstances.

Thanks for the heads up!
I'm not sure what's going on right now.

I'm trying to use Vegas as vid playback for my Reaper session (which has midi in it)

I am sending TC from Reaper using JS plugin and in Vegas I am using ASIO drivers. The problem is that when I hit play in reaper there is about a two second delay before Vegas starts to play....

Will do some more research and banging around and let you know if I make any progress....

cchoy "> there is about a two second delay before Vegas starts to play...." is normal; that's why I mentioned above, in the Advanced section, there is 'Synchronization delay' = 2sec, or even 1sec on a fast PC, as that is just the time for sync to be 'found' - all MIDI sync systems and DAWs need this time to work out incoming timecode and get going! If set too short you get either false triggering or no sync at all. So it's not good to start MIDI tunes at Bar1Beat1 = always leave a few bars count-in if you anticipate sync to other devices.

I can get Reaper to follow MTC generated by Vegas OK, but not the other way around at all; never tried that JS plugin though....pretty stupid Reaper does not gen MTC natively.... may find time to investigate that later; I do know that Reaper is fairly flakey even with Asio Positioning Protocol at some framerates (APP, which I prefer to use to sync to my main DAW as it is sample-accurate sync).

Edit, oh I see I can't use the word "s_t_u_p_i_d" ? The world is truly going mad!

Later: which JS plugin do you use to generate MTC? I can't see anything looks likely in the default installed plugins....