I don't plan to watch the video, but I can say with absolute certainty that frame connectors are a near necessity on convertibles. Both my wife's GTS and my son's Dart have stock suspension (small block and big block) and slightly larger than stock tires. No fancy traction aids on either car. The only change is that my son's Dart has frame connectors along with a much heavier engine (440 instead of a 340). You can feel the difference in body flex on a normal road. Due to its rarity, the GTS will not get frame connectors. We'll just continue to live with the flex. My Barracuda convertible got them shortly after I tore the car down.

I don't think they are as necessary on a street driven hardtop, but they still help.