It's hard for me to watch the above and not think we should give him a go in midfield. The driving runs and the passing range are wasted so far up the pitch. He also obviously has a lot of experience of patiently and selflessly creating chances for forwards who need a lot of opportunities to score.
That video tells me he's got a decent left foot, a decent shot from the edge of the box, and he can go past people. If he's not using those skills as much as we'd like right now (and he's not) then it's either because he's being told to do differently (in which case, question Pep) or it's a confidence/familiarity with the team thing (in which case, just needs time and patience).
It's not like we signed Kane and he's not scoring. It's Grealish. He's never delivered big g/a numbers. Nonetheless, Villa's win percentage under Smith is about double with Jack as it is without him. Yes, we play differently to Villa, and we'll never be as dependent on a player as they were on Jack. But he wasn't scoring and assisting every match to win them games, he was contributing in other significant ways. We're right to expect goal and assist contributions for him, especially if he's playing in the front line (and I think he expects them of himself), but let's be realistic - that's not and never has been his main strength.
At Villa he had a fairly free role, first centrally and later nominally on the left. He was their best player and his remit was essentially to go wherever and do whatever he needed to do to get them results. He was at a club with a coach who seems like a decent man-manager but who's tactically fairly poor, playing alongside average Prem players, several of whom were elevated by playing with him (look at the form of Matt Targett, who suddenly has no space, or Ollie Watkins, who suddenly has no provision). That he had the impact he did under seemingly so little tactical guidance and with so little real quality around him should tell us the quality of his footballing brain and his ability to adapt to different situations and change matches.
But I think his international career suffered because of the maverick reputation that free role gave him, and one of the reasons he came to City was to prove to Southgate and the world that he can be coached, can follow instructions, can fit in tactically with a team and be trusted to follow a manager's plan rather than just doing what he thinks he needs to. I think he's proving that but he's currently being too tightly managed to be properly effective, and he's not yet comfortable enough in the team to know when he can get away with taking risks or deviating slightly from his overarching instructions.
Long term he'll surely play midfield. He's the cover for and eventual successor to Gundo/KDB who are both great and still have a lot to offer but are ageing and getting more injuries, or to Bernardo who's incredible but reportedly wants to leave. His performances on the left-wing have by and large been par for the team's performance in any given match (which is impressive in itself considering he's new to the club, it's the first time he's had to stick so rigidly to a role, and that role probably isn't where he's going to play most of his City career) but he's going to struggle to stand out playing there under his current instructions.