Send IFTTT an email at trigger@applet.ifttt.com with a hashtag in the subject (e.g. #IFTTT) and this Trigger fires. You can optionally add a single file attachment (up to 30MB) and IFTTT will create a public URL to the file as an Ingredient.
This Action will create a video post on your Tumblr blog from the given URL to a YouTube video, a Vimeo video, a URL to a video file, or an embed code.