Ubuntu doesn't respond after playing YouTube video on Chrome

I am using Ubuntu 14.04 LTS 64 Bit OS. The laptop never respond, if I play any video on YouTube on Chrome Browser for 15-20 minutes duration. I have noticed that the right bottom side heats up while playing videos.

I found similar questions on Google but they somehow are not relevant here-

The laptop has following specifications-

• CPU: Intel Pentium N3700 @ 1.60 GHz
• CPU Speed: 1600 MHz
• L1 Cache: 224 KB
• L2 Cache: 2048 KB
• Memory: 4096 MB DDR3 1600 MHz
• Secondary Storage: SanDisk Z400s 2.5 7MM 128 GB SSD

Below are the Chrome Browser specific details-

• Google Chrome Version 51.0.2704.106 (64-bit)
• Adobe Flash Player - Version: 22.0.0.209
• Shockwave Flash 22.0 r0