Being a Finn i must admit, that this was really an excellent and informative video about our greatest composer. I only want to add one detail, because this was a Japanese video. During the years 1903-1904 the Finnish patriots and several Russian revolutionary movements were in close contact with Japan, which gave those groups money to buy weapons. That buying really happened and the grandfather of my wife had a rifle bought with this Japanese money. We have a photo about him and his friends with their "Grafton-rifles". It seemed possible, that there would be a war between Japan and Russia, and so in fact happened. For Japan this was an understandable maneuver to weaken Russia, and as we know, Japan won this war against Russia. That loss eased the pressure, which St. Petersburg had created against us Finns, but a few years later the second pressure period began. This time the WW1 weakened that pressure.
I enjoyed (,via the subtitles) your programme. 6th & 7th symphonies were composed in parallel with ideas for one ending up in the other, not the 5th. Tapiola, one of his greatest works, was composed after the 7th. There was little made in your video of Kullervo, Sibelius' first symphony, choral in Wagnerian style which really launched him as a composer. Sibelius suppressed it as he rejected that path.