UPDATE #2: Try v5.4.3. I’ve heard multiple reports it’s working fine for those who tried it. Let me know.
UPDATE: I just committed version 5.4.2. Try this and see if it fixes any problems. I couldn’t reproduce any errors on demand, but I made some code improvements to hopefully fix the problem.
I updated Viper’s Video Quicktags before WordPress 2.5 came out and it was 100% compatible then. Infact, it still is fully compatible with WordPress as far as I can tell.
However! It doesn’t seem to be compatible with many other plugins out there, namely ones that use the “ButtonSnap” PHP class that allows for easy adding of buttons to the classic style editor and old versions of TinyMCE. I’m working on fixing it, but it’s hard to debug it.
Meanwhile, the following work around worked for me: click the “Deactivate All Plugins” button, activate my plugin FIRST, then activate all the other plugins.
Thanks for being patient while I sort this out.