What means are you using to access media on your PS3? Network file server or DLNA media server?
If DLNA media server, where did you put the folder you created for your videos? Did you put it in a public share, or in a private share? Did you enable media serving for the share containing this video folder?
You can find out where the Twonky DLNA media server is searching for media by using its user interface. This thread might help:
