A good way to block these unwanted results is to filter them using LW's keyword filters. .wmv is a good start! See Influx of Porn recently being Spammed on Network - How to Stop it returning in your search results (click on link) & also autogenerated spam results

For videos might I recommend you get a backup player such as VLC which has in-built codecs & plays most things (without licence popups.) http://www.videolan.org/vlc/ (choose nearest mirror site)
Also worth seeing is Movie download issues & learning to use How to use Bitzi Web Lookup ...