Personally as a freelancer I don't recommend shooting by the hour. Remember to film quality video you have invested a lot of time and money learning video, invested in the gear, and there is actually more time preparing your gear and gathering the project requirements, which all take up your time. You are making the effort to make the trip and film. If someone is just looking for footage then I recommend you calculate your fixed costs and If you are starting out perhaps you could charge $50-100 an hour. I would recommend not working by the hour and instead charge either a half day or a full day rate. If you are an experienced professional and are providing quality gear (video, audio, lighting) then you can charge up to $800 US for a full day and $400-500 US for half a day. If you are in a job or are working a regular contract for someone you may have to settle for less.