In order to troubleshoot this issue effectively, I will need you to provide the following information:
1. Are you playing the Videos through RealPlayer or in the Cloud website?
2. What exactly happens when you play the video?
3. Do you receive any error messages? What does it say?
4. What exactly happens when you try to download it?
5. When was the last time you accessed these videos (was it before 6 months)?
6. Do you see thumbnail of the videos in RealPlayer or Cloud website?
7. What web browser do you use, and which version? (See https://customer.real.com/hc/en-us/articles/207275617)
8. What version of RealTimes or RealPlayer is installed? (See https://customer.real.com/hc/en-us/articles/204039513)
9. What is the operating system of your computer (Windows XP, Vista, 7, 8, 8.1, 10)?
10. Do you have any security software installed (Norton, McAfee, AVG, etc.)?
The more specific you are, the better I will be able to assist you.