Some footage needs it, but not all.
Look at the edges of moving brightly colored objects in the output, especially red ones. If the image appears blended you may need reinterlace chroma.
Closer inspection with a loupe (like xScope) should reveal an alternating chroma pattern. If the pattern goes like pairs of equal lines alternating you know that interlaced chroma was decompressed incorrectly.

Jan E.

Oops, I've deleted the original poster by accident.
These spam bots are making my life hard.

Jan E.