Video mobile optimised

Site URL: https://www.comms8.com/

Hi, 

I have questions on the Video mobile optimised. 
I showed a video on the home page for linking up a youtube link(as show in the attached pic 1). 
However, when it comes to mobile, the video is enlarge and widen (as show in the attached pic 2). 

May I know how I can make the video be mobile optimised? Or I need to re-do the video to make the title smaller?

Thanks!!