TL;DR: my home videos are taking up too much space and are impractical to backup on Dropbox. Which format do you advice to convert them to?
One year ago I bought a new compact camera (Canon SX230HS), so I could make nicer pictures and movies of my daughter. While the quality is a big improvement over my previous camera, the filesize of the resulting files also is a lot bigger, especially the movies. In the previous year I produced as much data as in the 8 years before. This is becoming a problem, because I’d like to backup everything on Dropbox, so I'd like to avoid having to backup several gigabytes a month.
I already configured my Canon to shoot in 1280x720 instead of 1920x1080, but this still results in 150 - 200Mb per minute in H.264.
Because those movies are only intended to be viewed by family and friends and posted on youtube/facebook, I'm thinking about converting them to another format. This will obviously lose some quality but I don't think this is a problem, afterall only 10 years ago people where still using tapes for this kind of recording with a lot less quality.
Which format would be best suitable for this? I was thinking WebM, since it seems the results are of rather good quality and because it is pushed by Google I would expect it to have a good change of survival and be recognized.
I'm a big fan of Open formats, so I would prefer the format to be open. But I'd also like it to be as portable as possible. It should be easily playable on most common devices, such as a tablet. (To my surprise this was not really the case on my Google Nexus 7 tablet. When I tried a webm-converted movie on the tablet it had serious problems playing it. I could only get it to play smoothly on the Nexus with the hardware decoder disabled in MX Player.)
Thank you for any advice!