you need an encoded file.
take a look here:
What Format are you exporting/rendering your video in? If you are exporting it as a AVI format it will be quite a bit larger. The best format for exporting To YouTube is to Use H.264 as this is well supported by YouTube and is usually a smaller size. Use smaller FPS such as 30 Because youtube supports no more then 30. Another thing you could do is render a lossless codec like animation then open media encoder and find a h.264 preset!
The default is Lossless which makes a huge file for further production work that probably will not playback in real time because AE is designed to produce shots that you edit in a non linear editor and then render for distribution. You can add an AE comp directly to the Adobe Media Encoder by simply dragging the comp to the cue in the AME and then pick one of the default h.264 presets that matches your frame size and frame rate. h.264 is the most common and most universally compatible delivery format right now. Next year the "best" delivery format may be different but for now use AME and h.264.
and one should mention that in CC 13.8, the long overdue feature of "Queue to AME" exists in After Effects Render Queue - Allowing you to get best of both Applications - After Effects Render Settings with AME's Output Module.
taken from the link - What’s New & Changed in After Effects CC 2015 (13.8) | Creative Cloud blog by Adobe
- Add compositions to Adobe Media Encoder with render settings: You can now send compositions from the Render Queue to the Adobe Media Encoder queue with the options you choose in the Render Settings dialog. When you click the new Queue in AME button in the Render Queue panel, queued render items are added to Adobe Media Encoder. Compositions will be rendered by Adobe Media Encoder with the render settings you chose in After Effects.
so no more motion blur turned off on your H.264 exports because Ae's Master Switch for MB was off
and no more having to change the export location in AME manually to the one you already set in after effects