I thought about this as well and came to the conclusion that just plain hard drives in a RAID is the most future proof in long term.
Bluray is only ok for temporary storage, a few months to a year. After that, just like with DVDs, you can't really trust the media. It's cheap enough (2-3$ for 25 GB) to have a 3rd backup on blurays but not as a primary backup.
Tapes are cool, lots of storage relatively cheap and in small space but like others said, you have the problem of continuously having to upgrade your tapes to whatever comes up next year or to keep buying tape reader/writers (and have some as backups) just in case they're discontinued at some point and your main unit breaks down.
Even though I respect free_electron and his experience, I don't agree with his suggestion of turning on hard drive, storing the data and then turning off the drive. Maybe it's silly, but I don't trust a hard drive NOT failing at startup all of the sudden, I'd be more comfortable with having the hard drive running 24/7 and potentially catching some error in close to real time and have the hard drive replaced.
I would go with one of those units that allow you to connect 4 or more hard drives and set up a raid5 or better and check from time to time the state of the disks and take corrective measures when needed.
In your case, you could have an identical unit at home (but maybe with other drives or another series just in case there's a bad batch) and you could just configure the home unit to slowly copy throughout the day what you have stored at the office (doesn't have to fast, it can be just 1mbps upload for example, you have it running 24/7 anyway)
Maxxarcade (of youtube "fame") recently upgraded his raid storage from a server with lots of ATA drives to a Synology DS1813+ (
http://www.newegg.com/Product/Product.aspx?Item=N82E16822108138 ) that can hold 8 hard drives, has 4 network ports that can be linked together for higher throughput etc etc. It's a bit expensive, but there's the cheaper
DS1513+ also which can only hold 5 drives.
I think it's a good investment if you're serious about backup.
PS. For extra security, you could use a tool like PAR2 to create recovery volumes for the video files. With about 20% of the video size in recovery volumes, you can recover pretty much any video file if it's just a bunch of bits or bytes messed up randomly (it won't help if there's a continuous 10-20 MB of totally damaged data)
md5sum and sha1sum will just make a checksum and that tells you if the file got corrupted or not, but par also is capable of repairing the files.