If you can use the 64bits one, they work better
32 bits Zip
http://avidemux.org/nightly/win32/avidemux_r8555_win32.7z
32 bits Installer
http://fixounet.free.fr/2.6/avidemux_2.6.3_r8558_win32.exe
64 bits version, should work fine, better than the 32 bits
Installer :
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http://fixounet.free.fr/2.6/avidemux_2.6.3_r8563_win64.exe
Zip:
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http://avidemux.org/nightly/win64/avidemux_r8561_win64.7z