Not sure I'd want to flick roll a -4. If you look under the fairing near the vertical fin you will see that the mounting bracket for said fin is only slightly thicker than bacofoil!
Having said that, I'm in two minds - the initial g-force in the pull up (3g) is consistant with flick entry (and unnecessarily high for an aileron or ballistic roll), and there is a visible left yawing motion left just before the roll starts - again consistant with a flick roll....
I have experienced basic aerobatics in both the -4 and the -8 and they're both very pleasant and capable aeroplanes.