Add controls to set start and end times for audio and video files when adding media to articles in Visual Editor
This is something that can currently be done in source editor like this
[[File:Example.mp4|start=2|end=6]]
https://www.mediawiki.org/wiki/Extension:EmbedVideo
This would vastly increase the usefulness of audio and video files on Wikimedia projects as it would be easy to chose to play only a section of a media file, often this is achieved by users by downloading, cutting and reuploading the file which is a complex and lengthly process.