I have not tried the last beta yet, but I had no problems with the previous 1.6 versions+kernelEx, except those bugs that everybody posted about.
To play videos I use a build from
MPLAYER which includes everything in one EXE, no need to download codecs separately. I have created a BAT file with the command line options that I like most (video and audio output), and I have all the video types associated with that BAT. Can view 3gp, flv, mpg, avi ,wmv and a lot more.
My useragent is:
Mozilla/5.0 (Windows; U; Win98; es-ES; rv:1.8.1.24pre) Gecko/20100228 K-Meleon/1.5.4