Sensory overload and incoherence are sadly the dominant qualities of this idealistic crowdsourced YouTube video project from director Kevin Macdonald and executive producer Ridley Scott, which is about everything and nothing.

It is a follow-up to Macdonald’s Life in a Day movie from 2011, in which legions of people responded to a request to send in homemade videos on what they were doing on a certain day in 2010: a time-capsule snapshot mosaic from all over the world. This time he and Scott put out a worldwide call for people to record all the various sad, funny, passionate or banal things they were doing on 25 July 2020; he got 324,000 videos from 192 countries.

Macdonald has edited all this down to an 87-minute presentation, which he has modified here and there with background music; some videos are broken up into micro-episodes and spread out over the collection, building in one case to a poignant twist ending.

A decade on from the first film, smartphones with higher-quality cameras have probably resulted in a technically more sophisticated haul; people have better equipment and are arguably more savvy about curating their content. More people are sending in drone footage with impressive high-def 4K images.

There are vehemently presented slices of life, with fierce comments on the Covid pandemic, racism, the climate crisis, poverty and inequality. Yet mulching all these themes together has the effect of giving equal weight to all the video molecules. It makes for a bland coleslaw of user-generated content, however startling and even remarkable the individual strands are. Exasperatingly, we are mostly not told where exactly they were filmed and the context-free mood makes it feel like a gigantic we-are-the-world corporate ad for life insurance.

There are some absorbing vignettes. A man proposes to his girlfriend in a beauty spot but is rejected; a Japanese woman tells her boyfriend (who is doing the filming) that she believes their relationship is doomed, and begins to cry.

Some of the videos don’t earn their keep on any level. A train-spotter kid makes it his business to film seven types of train on a single day in Illinois … that’s niche, to put it mildly. But I enjoyed the bored guy in lockdown who had given names to all the spiders in his apartment.

Easily the strongest moment is when a mother reveals that the adored teenage son who appeared in the first Life in a Day film has died of Covid. Macdonald may well have considered, if only for a second, making this film a complete follow-up for every single one of the people in that original, but discarded it as too close to Michael Apted’s Up series. And yet that mother’s testimony was powerful not merely in what it revealed but in its structural form. It had the compelling quality of narrative: that was then, this is now. The rest of this film is almost entirely formless. However moved or touched you may be by any particular moment, it is disconcerting to have that moment replaced by something completely different – tragic followed by quirky, funny followed by bleak – so you can’t process or understand the emotion.

This is a high-minded project conceived on an ambitious scale. But, for me, in the end there was an image satiety that was unrewarding.

• Life in a Day 2020 is screening at the Sundance film festival on 1 February, then available on YouTube from 6 February.