Think of it this way: Broadcast safe = $$$$.
If you are delivering videotapes for broadcast, then the broadcaster will give you a document outlining their “delivery specifications”. Amongst the many requirements will be something like, “Must conform to SMPTE 259”. This spec essentially outlines what a digital signal is and therefore, if you have to conform to this definition, anything “out of spec” is “out of broadcast safe”. How does this translate to $$$$? Well, most networks maintain large “QC” departments that pore over every submission very carefully. If your program varies outside of the specs, they will reject it, and ask that you resubmit a corrected master. This will cost you money to fix. So, if it’s your butt on the line guaranteeing network acceptance, then you’ll pay careful attention to things like Chroma, Luma, and blanking. Don’t forget VITC, closed captioning, and audio considerations.
A broadcast safe filter is essentially an “easy” button that supposedly guarantees that your output will pass muster. Don’t count on it. There have been numerous posts about sequences getting kicked back EVEN THOUGH the broadcast safe filter was applied.
Bottom line, if you’re distributing to any major broadcast or cable network, you will need to know about the technical aspects of the video signal you’re delivering.
Good luck.
Mark