I use a laptop with Windows 7. Firefox version is 39.0. I use internet through my university's proxy. The problem is that once I start watching a video on Firefox, as the video progresses, RAM usage constantly keeps increasing till the point where even my antivirus points out that Firefox is using a lot of RAM. I have only 4 GB RAM and Firefox starts at around 300-400 MB ends up using 2.5 GB of this and keeps increasing till the computer hangs. Once I close the video tab, the RAM usage holds steady. I have uninstalled all the add-ons. I tried uninstalling and reinstalling Firefox. It didn't work out. I am hoping someone here might be able to help me out. I can access YouTube only through this university's proxy.