Please follow these steps to resolve the issue.
1. Go to Control Panel and uninstall RealPlayer.
2. Go to https://support.microsoft.com/en-us/help/17588/fix-problems-that-block-programs-from-being-installed-or-removed and download and run the installer.
3. Once the Fixit program opens, click Next.
4. Select Uninstalling.
5. You will see a list of programs installed. Scroll down and look for "Video Downloader". Select that and click Next and click on "Yes, try uninstall". This will remove the application.
6. Run the Fixit program once again. (You will need to run this program a few times)
7. Follow steps 4 and remove the following programs (in the said order)
a. RealUpdgrade 1.1
Note: You have to run Fixit each time you want to uninstall these applications.
8. Delete Real & RealNetworks folders from
a. C:\Program Files (x86)
c. C:\Users\<your username>\AppData\Roaming
d. C:\Users\<your username>\AppData\Local
Once you have uninstalled all of them and deleted the folders, restart your computer. Download RealPlayer from www.real.com. Ideally, this should install properly.