resizing of preview in paper editing view makes text area smaller

[pietrop]

See the gif below (while using electron app)

if you resize the preview in paper editing it makes the text area smaller, making it harder to focus on the text.

Going to make a PR to remove the auto-resizing.

also note that as of version 7 of electron, chrome picture in picture is also available (see @bbc/react-transcript-editor implementation for example) as an option to give flexibility on size of video preview.