hey there, from watching your video I believe that extra 'hard drive' is the system reserved partition on your windows 7 install. but for some reason it has been given a drive letter.
If you delete this you may cause problems in your windows install.
go into disk management as you did in your video, right click the 100mb partition and click change drive letter. click on the drive letter and click remove and hit okay.
That will remove it from your 'my computer' but still leave the system reserved partition your computer needs without bugging you.
Just to let you know, this partition is NESSECARY. you cannot delete it. but you can stop it from appearing in your my computer page like I explained above.
If im wrong in understanding what your trying to say, post back and let me know and ill try to help further