Where there are brothers, there will always be sibling rivalry. As children they will often be at each other's throats, with one invariably convinced that the other is getting more attention and getting into a right old strop because of it.

And then they grow up and, well, little changes. There's always that hint of competition that the other is doing better than they are, or are simply just liked more.

Matt and Tom Beringer are definitely brothers that conform to these observations/stereotypes. Their sibling rivalry is heightened by the fact that Matt is the lead vocalist of indie rock outfit The National and Tom, well, isn't. Tom is Matt's younger brother, and it's fair to say that he's struggling with coming to terms with his brother's success specifically, and, just struggling with his role in life in general.

In what seemed like an attempt to help his younger brother out, Matt pulled some strings and managed to get his bro on a The National tour as a roadie. Although grateful for the gig, Tom has other ideas; he's going to make a documentary of the band on the road the likes of which has never been seen before, and he's not wrong.

Even spending half the afternoon blowing up Mr Crab didn't put a smile on his face.

On the surface, Mistaken for Strangers presents itself as a slightly quirky rockumentary. But after a while you realise that it's not about the band at all; it's actually about Tom and his changing relationship with his older brother. In magnifying the change in status his brother has undergone – from brother to international music star – it forces Tom to examine his own life, and he's not that impressed with what he finds.

As the tour progresses, it's blatantly clear to one and all that Tom isn't focused on being a roadie. For one thing, he isn't very good at it; for another, he's wrapped up in the whole film-making process. It's just a shame that he's the only one that is.

Matt tries his best at being supportive, but he's got his hands full with the whole pop star thing. And if everyone thought Tom was a bad roadie (which they do), his skills as a documentary maker are seriously lacking. Thankfully though, and somewhat surprisingly, this is what gives the film its warmth and charm.

At times, Tom is like the winner of a competition to tour with a band that he's not all that into, who quickly becomes disillusioned at how disappointedly un-rock and roll it all is. At others, it feels like Homer Simpson has got behind a camera and has somehow managed to follow The National around.

Tom is the Rocky of documentary makers; he takes a fair number of knocks and punches along the way, but he puts on a brave and valiant fight, right up until the end.

It's unlikely that Mistaken for Strangers is going to increase the fan base for The National, but it may well have made a star-in-the-making in Tom. Just as long as he doesn't make another rockumentary. But if he did, you know darn well that you would have to watch it.