The squarewave picture shows 75 fps. This corresponds to the compact disk time code with 75 frames per second.
The displayed time are to be interpreted as hours:minutes:seconds:frames. So e.g. 00:00:01:07.5 means 1 second 7.5 frames. 7.5 frames corresponds to 0.1s (=7.5/75). Result: 1.1 seconds.
The squarewave has a cycle time of 0.25 frames = 0.00333... seconds. This means we have a squarewave of frequency 300 Hz.
Now a squarewave consists of sinewaves of odd order = 1, 3, 5, 7, 9, 11, 13 ... With the given 300 Hz this results in 7 frequencies up to order 13 = 300 Hz, 900 Hz, 1500 Hz, 2100 Hz, 2700 Hz, 3300 Hz and 3900 Hz. We can now check the spectral lines and we can clearly count 7 lines up to 4 kHz.
This means: the displayed data are very correct.