Adding a quasi-LICENSE file.

LICENSE.md

@@ -0,0 +1,13 @@
+LGPL.
+
+The license text for this code is in the source files.
+[LICENSE files do more harm than good](https://yahweasel.github.io/license-files-considered-harmful/).
+
+This file exists because some people expect it to be here.
+
+libav.js builds include correct license headers. Do not remove them.
+
+If you make modifications to this repository that involve modifying the
+underlying FFmpeg code, you are *legally obligated* to share those changes. If
+you do not, you are in violation of FFmpeg's license terms. I'm looking at you,
+“my startup is too cool to read licenses” scumbags.