These two Axis Flow tutorial videos are a good place to start. They cover the basics and move at an easy-to-follow pace, demonstrating moves both with and without flags in hand.
This page from Desert Flaggers has short, simple videos that are clear and easy to understand. They're divided between Novice, Intermediate, and Advanced moves.
These five videos teach more advanced moves. The videos are a bit longer but very comprehensive and helpful for more difficult moves. There are also additional videos on this flaggers YouTube page.
Facebook group providing information about events friendships among flaggers around the country (and Brazil!). Find it HERE.
Facebook group that offers information for flaggers, fan dancer, poi spinner and other flow arts who gather monthly in San Francisco. Find it HERE.
Facebook group in the Coachella Valley sharing information about the artistry of flow flags, poi, or fans. Find it HERE.