FreeRapid Downloader is a free program that will solve that problem. It can deal with Megaupload and Rapidshare processes. You won't need to visit the website, so your downloads will be in your computer sooner.
You can add one or several download links at once. It's very comfortable if you have several links. Just add all the links and FreeRapid Downloader will do the rest.
It will wait for the specified time and will feature the captchas in the same interface, just enter them and the downloads will go on. If the download service allows pause and resume downloads, FreeRapid Downloader also brings that option to you. IF you usually use this kind of service, it can be a good choice to manage your downloads.
It requires Java.