I looked for it, but the original study hasn't been released, so we can only speculate based on the press release.
Wellbeing increased by 21% from just 20 minutes of gig-time, compared to just 10% for yoga and only 7% for dog-walking
They probably asked people how good they felt 20 minutes into the concert. Better than after doing yoga, that's plausible. But there is no reason to assume you feel better after the concert ends - if it did they'd mention it.
They want to imply that going to concerts will bring permanent benefits by arguing:
Accompanying research showed a positive correlation between regularity of gig attendance and wellbeing.
A positive correlation could be something like r = 0.03 (almost nothing) - we don't know. But one thing is always true: "Correlation doesn't equal causation". It's more plausible that extroverted people - who are happier on average (many studies, for example: http://psycnet.apa.org/record/1981-10468-001) - seek out more concerts.
additional scholarly research directly links high levels of wellbeing with a lifespan increase of nine years
I don't know what research they are referring to here. Most papers in that direction face the difficult question "Are these people healthy because they are happier or are they happier because they are healthier?".
This study suggests that "positive affection" does make you live longer, even when controlling for other factors. I don't know how to convert an odds ratio of 0.962 (for mortality) into years (maybe somebody of you does). But considering the fact that we don't have proof for concerts permanently increasing your happiness, we can also be skeptical that they will increase your lifetime by 9 years.
Additionally, if concerts increase your happiness permanently, they will only be a small fraction of what makes you happy, so talking about 9 years is in no way appropriate.
Please prove me wrong, but as it stands I'd call the articles "clickbait with no basis in reality."