1. Are you still trying to enter the BaSPl from a frog stand? It is significantly easier if you get into the position the way the athlete in the video demonstrates.
2. Your PPP strength is lacking as demonstrated by your form in the video you posted. In my opinion, the most productive way for you to build the bent arm strength required for holding this position would be to fix your PPP form and re-master the exercise that way. Holding the BaSPl is not much harder than a PPP with good form and hands by the hips; if you can do 5x10 PPP with good form, you will certainly be strong enough to hold the BaSPl.