We can not fetch videos from this type of page.
Your URL was: http://download.asp?videolink=https%3A%2F%2Fwww%2Eyoutube%2Ecom%2Fwatch%3Fv%3Ds7rtRDLfpXE
The URL must be like http://www.youtube.com/watch?v=KPtX7hak0Qs
https://www.
and replace with pwn
Example: