relates to #8841
relates to #18531

Issue Context

• Issue is visible on the amp-ima-video AMP By Example.

• Source code for the video player of <amp-ima-video> can be found in ads/google/imaVideo.js.

• Currently, we are designing/considering a rebuild of video within AMP to use Video.js, so smaller issues will be considered as we don't want to dedicate too much time on the older component version.

Issue Description

When an ad is playing there is no way to exit full screen, or mute the ad, due to a lack of controls when an ad is playing.