I should be able to see a solar eclipse from my home in Japan on Wednesday 22nd July.

It will be a near total eclipse from here.

Does anyone have any experience of videoing such an event?

Advice? Don't do it! Do it this way! Look out for! etc.etc.
All help welcome.

Regards,
Douglas

PS. Probably has no bearing on the topic , but I will be shooting with a Sony Z1 and a Sony FX1.

I will be on the centre line in Shanghai. I am leaving Saturday for China and will be on a beach to watch an eclipse for the first time myself. I can't offer anything from personal experience but I have found this:
Eclipse Photography - 3 (http://www.mreclipse.com/Totality/TotalityCh12-3.html)

You will need a solar filter to video during the partial phases, but after that I am not sure. Good luck with clouds!

Looking forward to the footage, but as a general safety reminder do NOT look at the sun either directly or through the a camera optical viewfinder. Here are a few threads from past solar eclipses and sunrise/sunset shoots:

http://www.dvinfo.net/conf/open-dv-discussion/62349-recording-solar-eclipse.html
http://www.dvinfo.net/conf/sony-hvr-a1-hdr-hc-series/63259-safe-shoot-sun.html
http://www.dvinfo.net/conf/sony-hvr-z1-hdr-fx1/61603-capturing-solar-eclipse-z1.html
http://www.dvinfo.net/conf/open-dv-discussion/51687-shooting-sun.html
http://www.dvinfo.net/conf/open-dv-discussion/5024-shooting-solar-eclipse.html

How much "sun gazing" can a camera take without damaging the sensors?

FWIW, I have shot stills -- not video, but it should work --- using a #14 welder's helmet filter. You can get them in, iirc, 3 1/2 x 3 1/2 inch size fairly cheaply at welding supply houses.... hth / Battle Vaughan /miamiherald.com video team