Video Editor - how to play video and find a specific place

I am trying to edit a mp4 podcast video.
I want to extract a section from the middle.

I have brought it into blender 2.8 video editor but when i try to play it to find the rigth place it jumps back to the start and just plays a tiny loop of it there.

Any help with this please?
I can’t upgrade to the latest blender as it doesn’t like win7

Is your mp4 longer than the start and end frames (defaulted at 1-250), in the output properties >> dimensions >> frame start, end? Just guessing here, the only thing I can think of why it would be looping only a small section.