I recently download mplayer for some videos that nothing else would play and it works great, but I wanted a front end for it. I downloaded the latest portable version of SMPlayer because I prefer programs that don't make changes to my system. Unfortunately, although it works, it has numerous problems.
1. When using the File > Open menu item and you enter a directory with more than a couple video files, SMPlayer goes off into limbo. The pointer changes to an hourglass but nothing ever appears in the window. For the first several seconds, it can be closed normally through the Task Manager. If you let it sit for a couple minutes, the Task Manager will report that the program isn't responding and you have to kill it.
2. Once you get a video loaded, either by dropping one on the window or by going to a directory with only a couple videos in it, most of the controls are non-functional. The volume slider visibly moves, but the volume is always at 100%. Clicking the speaker icon to mute the volume doesn't work either. The seek bar moves as the video plays, but attempting to move it manually has no effect, it just jumps back to the previous position. Pause doesn't work, either by using the spacebar or the pause button. The stop button works, but causes mplayer to crash and then SMPlayer reports that mplayer "finished unexpectedly" with code 62097.
3. If I close SMPlayer while a video is playing, it reports that mplayer has crashed.
I know not many people use Windows 98 anymore, but for the time being, it's what I have. SMPlayer says it works on 98, so I'm just reporting my experiences with it.