Blues Bros. is interlaced. Open the file in
Virtualdub and apply the built-in yadif deinterlace filter set for double frame rate, top field first. Advanced the video one frame at a time with the navigation icons in the lower left corner. With the yadif filter turned on, the left-hand input frame will show each frame as-is, unaltered, the output frame will show each
field in succession, one field at a time. With each click of the frame advance button the output pane during motion will show a different image (look at the hands when they move, or look at Balushi moving). The images will play in the
output pane as A-B-C-D-E-F and so on. A different image with each click indicates that the video is interlaced.
A duplicate frame with two clicks in a row during motion would indicate progressive frames. This would play as A-A-B-B-C-C-D-D and so on.
A duplicate clip for more than two clicks in a row interspersed with a sequence of only two dupes in a row indicates some form of pulldown. A typical pulldown would play as A-A-B-B-C-C-C-D-D-D-E-E-F-F-G-G-H-H-H-I-I-I or something similarly weird. Pulldown schemes consist of progressive frames interspersed with frames that appear as interlaced.
Try the old Neuron2 hmtl page (now removed from the internet, for some strange reason) for clues about how to "read" frame structures.
Neuron2_How To Analyze Video Frame Structure.zip.