On top of the obvious fix needed to both your AUDIO and VIDEO looping problem, where the loops are not smooth and they clip once they reset, I believe you would benefit greatly from this feature:
At the momment every screensaver installed creates its own folder in the start menu, this is very spammy if people install many screensavers from your company. Editing the directory area to specify c:\program files\your company\ would mess up windows xp/vista systems and not show the entire screensavers on the screensaver option tab.
The software should:
A. Ask what the company name is for the screensaver.
B. Install the screensaver file in c:\windows or c:\windows\system32 depending on OS detection.
C. Make a folder in C:\Program Files\COMPANYNAME\screensavername | Or ask the user where he wants the COMPANYNAME folder to be
D. Add to start menu START > PROGRAMS > COMPANY NAME > screensaver name
This way all the screensavers for said company would end up in the same place in a different folder but under ONE company name, reducing the spammy method used now.
ps: fix the looping issue with sound/video.