Look in Skill tree for that attack ability. Look at "Cost". Can't tell for sure, but from the video it sounds like you are using a Stamina based ability and it stops working when your stamina gets too low and you no longer have what it "costs". You are stuck without that attack until stamina regens.

If that is the case, look at where you can invest char/skill points to increase max stamina or regen, and combine that with foods/drinks/potions to try to avoid running out like that.

Sorry, just taking a guess because all I can hear very clearly is the loud clicking sound that happens when button is spammed but stamina is empty.