Upside is that these are usually lighter in weight, and thus faster to load, downside is that these can't always achieve the 'coolness' of video effects.
3. animated svg
SVG is a vector graphics format, so best suited for vectorial images (since you're using PS, I'm assuming that might be a problem). The upside of using an animated svg is that you can save it all to one file and just put it in your HTML like any other image. Downside: IE isn't playing along nicely.