I needed to export a single clip from my timeline within FCP for a jpeg. This I know how to do, though my final product is always squished and distorted. My frame size in FCP is 1280x1080. I find that when I shrink my frame size down by exactly half and then drag a clip out for a jpeg, it looks perfect...which doesn’t make any sense to me. I’ve been exporting it under ‘Quicktime conversion’, and then I click on ‘still image’.
Your footage is DVCPRO HD. This is an anamorphic format... The pixels are not square. The image is 1280 pixels wide, but stretches to display as 1920. Computers display still images with square pixels, so you need to stretch the image in Photoshop to 1920 x 1080.