Columns of dashed lines that extend down into the picture are definitely copy protection. Here's a wicked case, shown on my 1961 CTC-11.
Google for "video stabilizer" to find inexpensive devices that will let you play your copy-protected DVDs on your old TVs without this annoying hash. Different TVs respond differently to this stuff, and I imagine there are different copy protection schemes. In any case, the stabilizer lets me play any of my DVDs on any of my old TVs.
This is different than the other two hash sources mentioned (the thin horizontal row of dashed junk at the extreme top, and the widely spaced diagonal lines).
Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html