Assuming you have two Android devices named respectively X and Y:
– Open the Wifi Settings on the two Android devices (Long press on the Wifi icon).
– Disconnect from the current network, if any.
– In the top-right corner, click Wifi-Direct. X should display Y as availble, and vise-versa.
– On X, click to connect with Y.
– On Y, you will see an invitation for a connection. Accept it.

Now run BubbleUPnP on device X (or any other UpnP or DLNA server).
Go to More > Parameters (a gear icon at the bottom left) > Local and Cloud > enable the remote browzing.
And in the Config section “authorised media” fro remote browsing, enable video, music, …

You should now be able to run any UPnp (or a DLNA) client on device Y and see media from device X.

Ex.: run BubbleUPnp on device Y, click at the bottom-right on the “Library”.
You should see “Local and Cloud” and “BubbleUPnP Media Server (Device X)”.
Pick “BubbleUPnP Media Server (Device X)” and now, you have access to the Library of your device X.
When you open a media, BubbleUPnP will use your favorite player (mine is MX Player)