So no termination. With the Arb set to 50 ohm, I am guessing the readout is then off by a factor of 2X, or really 240mVpeak or 0.169 RMS.
Still, with the one I have, using no termination, 200mm of RG400, setting the RF generator to even 35MHz and changing the amplitude, I can find a sweet spot where it comes in. This is why I was asking about you changing the frequency and amplitude in the video to give me some idea how well yours detects the signal.
With your second source, is that 950mVpp without the termination? When I tried to square it up with the LVDS and PECL drive, it made no difference in how my meter behaved.
Both are not good compared with what is stated but I'm surprised yours behaves differently, especially after rsjsouza's post showing the exact same error in the frequency I see with mine.