MS Paint works great for blurring faces and other identifiable details. When you select 'file' 'save as' you can change format to JPEG or whatever you prefer. For cropping, I use one called Photopad from NCH. It has some effects too but I haven't had much use for them.
I still use Windows Moviemaker for video editing but it only works with certain formats. To convert, I use Prism Video converter from the same company. They offer free demos of their software but after clicking through and declining a few times, they stop bugging you to buy and let you keep the trial version. They aren't full function but they work well enough that I've considered purchasing the full version of both. Here's a link to their site.
http://www.nchsoftware.com/software/index.html