The same here. I uploaded a mp4 media file (13 MB) and after uploading the full 100% this message was displayed http: error
Both ways the same, Flash or Browser Uploader.
(WP 4.2.4 / active Plugins: Contact Form 7 + IE DatePicker and Number Spinner Fix, Include me / active Theme: Twenty Fourteen)
Deactivating the Plugins didn’t help.
Do anyone have an idea to solve that problem ?
In my case it is not a problem with the provider !
All media files even the already uploaded mp4 files are still there and available !
