@Martin53,
There is a known Overlay bug in v2.6a4, here:
http://forum.doom9.org/showthread.ph...03#post1624303
Use Groucho2004's ICL Avisynth.dll with fixed OverLay for YV24. (just overwrite dll in sytem32/SysWOW64)
EDIT: Groucho, Local is for the GScript version Scriptclip. EDIT: Actually Grunt, not Gscript.