I'm sending a movie via email.
Will a file encoded with the ffmpeg's option
libx264, be able to play back natively in Windows 8 without any external software?
ffmpeg -i in.avi -vcodec libx264 out.avi
For further info, I'll point you to the answer I've posted here: What is a Codec (e.g. DivX?), and how does it differ from a File Format (e.g. MPG)? This goes way beyond what I'm writing here, but for this question, we can narrow it down a little.
What is x264?
So, first of all,
Because there's just a codec standard, there are many other H.264 encoders apart from x264 such as Mainconcept or even a built-in one from FFmpeg. But x264 is free, open source, very efficient and delivers good quality, which is why it's used so often.
Why do we need a container?
x264 can only encode actual video. You could theoretically just store it in a
A container will synchronize video and audio frames according to their Presentation Time Stamp (PTS), which makes sure they are displayed at exactly the same time.
Popular containers these days include …
To sum it up: Codecs are stored inside of a container. Codecs represent the actual media, and the containers just bundle them into one file. You could call them both "formats", but don't use that term because it's ambiguous.
x.264 is an H.264 / MPEG-4 Part 10 encoder. H.264 codecs are supported:
It should play in Windows Media Player by default (x.264 is an MPEG-4 Part 10 / AVC encoder, which is supported). However, Windows Media Player does not necessarily ship by default with Windows (I think this is due to antitrust issues in Europe).
Not quite related to your question, but why not consider hosting the file online (YouTube, Picasa/Google+, Flickr)? Then your recipient just needs a web browser.