I have found google drive (with many extensions) to be about the most useful tool for editing file types but (as discussed in the paper I shared earlier) there are international differences between how copyright laws are applied that can make remixing more problematic than just changing a file type. 

I created this set of resources for language teachers to help navigate the complexities of using video in language teaching, it also links to some EU funded work on video I was involved in. The issue I have is this: once tools are made available (such as WIKIspaces used in my example) the real motive of the provider becomes clear - if there is no funding model eventually they withdraw the tool. This is a real risk to those of us creating in these spaces (always have a back up plan!) Even good guys like Mozilla stop supporting the tools which could really help open practitioners once they have a new focus. The digital environment is a rapidly evolving one where one can quickly fall victim to "format frenzy". Increasingly I look to the open source movement to support educators, proprietary formats are expensive and lead to "lock in" - commercial pressure to buy the "right" hardware to playback etc. I think it is important that those of us involved in the open movement work together to ensure that the advantages of "open" remain and do not get "owned" by large corporations, at the very least we should insist that there is a moral duty to open education and learning to all.