Rapidshare and rest of the download sites are recognizing clients by IP address and cookie planted in your browser.
To avoid wait times follow the steps bellow:

1. Go to Start->Run and type in cmd Hit Enter.
2. Type ipconfig /flushdns and hit Enter.
3. Type ipconfig /release and hit Enter.
4. Type ipconfig /renew and press Enter: Now you will recieve new IP address.
5. Now open your browser and delete cookies.
6. Run download from Rapidshare or Megaupload again.

Note:The guide works only on computers with dynamic IP address, if you are behind Router it will not work