First to view, first to comment. Mamma Mia is a popular song, but not their 'best creation' by any means. Dancing Queen is perhaps the best known, but there are many other songs which are better known and better liked. Abba was big in the middle 70s to early 80s, and not just 'the late 70s' as you said. Waterloo started the fame in 1974 of course., though they'd been working together since 1972. "Sadness in their music" towards the end? SOS, Knowing me Knowing you were two very sad songs from the early days. Chiquitita is quite mournful, One Man one Woman, The Winner Takes it ALl., Fernando and more are all sad songs from they peak years. Abba has always had upbeat music to sad ideas. Your discussion was very much based on surface observations (that's fine in a 5 min video) but it tended to package everything up into neat and tidy ideas which simplified what happened and the evolution of the group into easy-to-eat nuggets that are so bland or so full of platitudes as to be meaningless. A good try, but too much focus on your 'house-style' and your desire to create a narrative to fit your format. The medium has become the message here, alas, and so all we're left with is a mixed confection or cliches and some brief video shorts, with an announcer using his best and most reassuring voice to assure us that there's no need to have bad dreams, as it will all end well and the we'll reach a nice safe normality with no troublesome nuances to make the journey rocky.