You can find the task scheduler here:
Start - All Programs - Accessories - System Tools - Scheduled Tasks
Follow the Wizard
Select Windows Media Player
Select Daily, Select start time etc.
Check 'open advanced features for this task when I click finish'
Click finish and in the advanced properties edit the run box
Add the path and filename of the file to run
e.g., ...\wmplayer.exe "C:\temp\OneMinute.wmv"
Click OK and you will have to re-enter your password
You can go back to the folder that had AddScheduledTask and your new task will be visible.
Right click and select Run to test your setup
If you get an error, make sure that the path and filename are correct including upper case/lower case characters.