Okay...start off with describing your set-up. Is it a stock A500? Does it have a HD, do you boot from floppy? What software are you using to do the videotitling? Do you start your software from workbench (AmigaOS's GUI) or is it on a selfbooting floppy? Sorry bout all these question, but you're not giving much we can work with :-).
Oh! Welcome to A.Org :-D!