Ethovision is not the best free software, because it is not free. Have a look at this paper (Dell et al. 2014; link 1) and its supplement (link 2) for a list of some possible software:
I've done a similar question and someone recommended me BORIS, a FREE software that seems so easy to understand but I've seen JWatcher as another possible option.
We offer a secure cloud-based app that allows you to automate your animal behavioral research.
It can be accessed anywhere in the world by a computer, smartphone, or tablet without downloading anything.
Wouldn't it be amazing to do your behavioral analysis in front of the TV watching Netflix...
You don't need anything fancy in order to get started, typically you can set up your smartphone, and let it record, while you're in a separate room. There is no fear of an interruptance caused by a researcher, etc.
Although we are not an open-source program. Our prices are very competitive when compared to Noldus' EthoVision. You can even share your data with your collaborators.
Please feel free to start your free trial at www.behaviorcloud.com or email me at [email protected] for more details.