I created a video
here Make sure you select 720p or higher and full screen.
I'm adding this now without instructional text right now because I've been feeling under the weather lately and if God forbid I end up in the damn hospital I wanted to at least get this out there. No, it's not the China flu. Attached is the sample batch file you'd use. Make sure you change the paths to reflect each folder month. So in this batch file the path is C:\test\1.wmv or C:\test\2.wmv, etc. So you'd create 12 folders for each month under C drive so your paths might be, C:\January\1.wmv, C:\January\2.wmv, etc all the way to video 20. Then you'd have a batch file for February. C:\February\1.wmv, C:\February\2.wmv, etc. Just name your video files 1 through 20 to make it easier. Create January through December folders under C drive and in each folder month would be that month's batch file. Then you'd create 12 separate tasks for each month. Each task would fire off that month's batch file. Make sure you edit the part that says "else if %number% equ 2 (", else if %number% equ 3 (, etc. so 4 then 5 then 6, all the way to 20. And at the very top instead of %RANDOM% %% 7 + 1, it be 20+1 since you have 20 videos so the random number generator has to pick from 20 videos from that month's folder.
Again. Each month needs its own folder.
Each month needs its own batch file tailored to its folder month path.
Place each month's batch file in its own month's folder.
I could make this all for you. I see that I can export Task Scheduler tasks that you can import and I can create each batch file for each month for 20 videos. You just have to rename each video 1 though 20 in each month's folder. So 20 videos in January's folder numbered 1 though 20, and 20 videos in February's folder numbered 1 through 20, etc.
So yeah, choosing the log on option in Task Scheduler will fire off the batch file for that month per login or reboot to pick a random video from 20.
If you need help and I'm not here perhaps someone else can help.