It's not glitched at all. After you get a kill and activate the shield any subsequent kills don't proc (and don't use a melee charge) because your previous overshield is still active. Otherwise it would be a waste. Why use another charge if your overshield is still active? At the start of the video your overshield is completely removed by damage and so will not regenerate. At this point the overshield perk is still active and subsequent shotgun kills will not activate the overshield until the children has gone. It makes sense, coming from someone who mains a Titan and appreciated this build. Edit: actually, in PvE with thagomizers I can melee twice in a row and activate a second charge immediately... I wonder if it's worth testing those in PvP and seeing if they work differently? Thought I'd leave my original comment though as I believe that's what Bungie would intend in PvP...