They're not spaced properly, two of them are touching each other and then there's a spot where there's 2 spaces next to each other

https://www.gog.com/forum/wing_commander_series/privateer_2_unofficial_patch_thread
Those aren't scanlines, the video is interlaced because at the time these cutscenes were horribly heavy on the hardware so they didn't render the complete frames even though the monitors were already capable of doing progressive scan and the video files used were natively progressive instead of interlaced, you can use a patch provided in the link to get rid of it.

That screenshot is not natural, this poor spacing of the lines is most likely caused by the resolution used, shader or video outputmode in Dosbox. If you aren't going to use Det_Bullock's suggested fix, which I recommend, try different screen resolutions, video output and shaders to see if it goes away.