Install Minidlna to stream media from the Raspberry Pi.
Use a Wifi dongle to create a hotspot
Then all you need is power to be able to stream media from the Pi via the hotspot to a device which connects via wifi.
MiniDLNA is a DLNA server designed to stream media from a central repository to DLNA clients. This means that any device that can run a DLNA capable media player will be able to view video from the Pi, TVs, Laptops, Mobile Phones, etc.
VLC can be used from a PC/Laptop
I use Skifta on my Android mobile, but I'm not sure what players iOS have.
Running a hotspot from the Pi will allow wifi access to the DLNA server without having to setup a separate device to allow access over wifi. Using a RT5370 device would be the easiest IMO as it's plug and play when it comes to hot spots.
Simply install hostapd and dnsmasq, configure hostapd to your needs, and configure dnsmasq with these 2 lines -
and then set a static IP address of 10.0.0.1 on wlan0, and away you go.