First, and most important is that you need SD card what works enough fast with UltraSatan. May work with Gigafile too.
So, first test your SD cards for transfer speed.http://atari.8bitchip.info/ahpt.html
Use Transfer rate test at left. By need set proper ACSI Num. Required transfer rate is min 1100 KB/sec . And that's what
is not case with many SD cards, even if they are very fast normally - when using with UltraSatan .
Next thing is that partition from which you want play video must be defragmented. You need at least 300 MB part. for this .
The video with player SW: http://atari.8bitchip.info/LavCre/P158A1.rar
200 MB. Pretty amusing way of getting rid of clothes
You may try it in emulators too. There is player version for IDE hard disks too, but you need to byte-swap HAV file if using DOS partitioned CF card. Playback from classic hard disks is not good according to my tests. Only fast Flash cards are OK.