Video needs its own folder within root, can't be in the /PS3/ folder. /PS3/ is only for backups.
File structure has to be exactly like this:
http://ps3explained.com/advanced/folder-structure/
For ps3mediaserver...are you running it on windows or os x? On os x you just need to select the correct network adapter and save it.
If you can't get it working on windows there are a lot of dlna servers that compete with it
http://en.wikipedia.org/wiki/Comparison_of_UPnP_AV_MediaServers
try Twonky if all else fails.