And also have a download button on the YouTube page itself.
Well there is now a script you can install on your browser( this script is compatible with all browsers).
It is easy to install, and free. You can obtain the script from here.
To help you there is a handy little video here by Bill Myers on how to install the script.
If you want to download your video from another Video Hosting site such as Vimeo a free tool you can use is Keepvid where you enter the URL(unique resource location ie website address) of the video you want to download.
You can also get a Keepvid button for your browser.
Hope you find this useful!
PS: Have you heard of etoro? If not check out the link below.