I am not entirely sure what you mean. But from previous talks with you I know you want to make some sort of botish program that will do commands depending on user-input.
So I am guessing you want to do something like this:
' Generic command structure: command;argument;argument;argument;argument;argument;
' Command to play video: video;http://youtubeurl.com;
Dim CommandArguments() as string = UserInput.split(";")
If CommandArguments(0) = "video" then
process.start(CommandArguments(1))
' If you want to play other types of videos, like black out the entire screen and play a fullscreen video, you have to look into the windows media player control or directx etc. Look at this; http://www.vbdotnetforums.com/add-development/1701-playing-video-clip-form.html
End if