It'd still be good to know if MS button #2 works in G-Spot. However, since the G-Spot screenie seems to show that the Render is okay, and that it is using the proper render path my guess is:
(a) Something broke or is misconfigured in MC's DirectShow Playback Settings dialog. However, this seems unlikely because you said that the videos also don't play in MPC and other players (VLC isn't really a valid test, but Windows Media Player would be).
(b) Your qdv.dll filter got corrupted or borked up in some way.
(c) Whatever software you used to capture the videos requires some weird and specialty DV decoder.
So... The things I would try in order:
(1) Make sure to reset all of the AVI decoders in MC back to their defaults. Go to
Tools --> Options --> Playback --> DirectShow Playback Settings. Then on the Right under
DirectShow Filters, choose AVI (check the box if it isn't already) and click
Select Filters. Then on the left side under
Source Filters, scroll through the list and uncheck
EVERYTHING. On the right side under Other Filters scroll through the list and check ONLY
JRiver Bitrate Monitor filter. Under Video Renderer, select
Video Mixing Renderer 9 (if you have Windows XP). Your dialog box should look like this:
(2) First, turn off System Restore temporarily. Right click on My Computer (on the Desktop or in the Start Menu) and choose Properties. Switch to the System Restore tab in the window that appears and check the Turn off System Restore box. Click OK.
Find all copies of qdv.dll on your system and rename them to qdv.bak. Do this by going to
Start --> Search --> All Files and Folders, put
qdv.dll in the file name box, and hit
More Advanced Options. Check the boxes for
search system folders,
search hidden files and folders, and
search subfolders. Make sure Look In is set to C: and click Search. When the results appear, select each copy in the search results list (one at a time)
Right-Click --> Rename and type
qdv.bak.
Next, download the latest DirectX distribution from here:
http://www.microsoft.com/downloads/details.aspx?FamilyId=2DA43D38-DB71-4C1B-BC6A-9B6652CD92A3&displaylang=enNext, REBOOT! DON'T SKIP THIS STEP!!
Lastly, reinstall DirectX using the installer you downloaded from Microsoft.
Then you can re-enable System Restore (just uncheck the same box as you checked before).
(3) If this still fails to correct your playback, then I would definitely try reinstalling the Video Editing application that you used to capture the videos initially. Perhaps it is using some weird non-standard DV codec.
(4) If that fails, I might be completely out of ideas. I'd really honestly say the best option might be a nuke/pave (complete wipe and reinstall of windows). That's drastic though, so perhaps someone else will have some ideas first.