Here's the video:
This solar flare came from a very active sunspot that's just rotated around to our side of the Sun. Sunspots look like dark spots on the Sun, they're areas of increased magnetic activity which keeps the hot material from rising to the surface, so it's cooler than the surrounding areas. Here's a picture of the sunspots on the Sun right now, the one labeled 1429 is our culprit. Note it's about 4 times larger than the Earth (see the scale at the bottom right).
The magnetic field lines coming out of a sunspot are shaped like long tubes, called flux tubes, and they're connected back to another sunspot. As the Sun rotates, the tubes connecting a pair of sunspots gets twisted up, storing magnetic energy in the twist. Eventually, they twist up so much they 'break' - the field lines reorganize to a less twisted shape, and the stored up magnetic energy is released. There is a sudden brightening as the energy is released - a solar flare - and big clouds of plasma can be thrown off into space - a Coronal Mass Ejection, or CME. Sometimes, those clouds of material get thrown in the direction of Earth, and this happens.
The flare above wasn't directed at Earth, but it was close enough that we'll receive a glancing blow from it. It's expected to hit on Tuesday or Wednesday. The thing is, the same sunspot spit out a flare on Sunday that's also expected to arrive on Tuesday. We might get hit with a double whammy here! I'm hoping for clear skies, maybe we'll get a good show.
Sunspot 1429 is producing multiple strong flares and currently rotating to face Earth, so we should expect more excitement over the next two weeks or so.