Export video from After Effects for Web Banner as HTML5

I have an 10 seconds video done in After Effects CC 2015 with 300 x 600px and need to work as a Web Banner.

We need to supply it as HTML5 and the Media Guide needs it with maximum 40Kb.

I have read many tutorials but since FLV and SWF are not in After Effects or Adobe Media Encoder, I don't know how the process would be.

Please help us.

Thank you,