My first brickfilm (called "LEGO City") runs only 34 seconds, but was made in the summer of 1979 (in Dallas, Texas). I was 12 years old.
The film was lost for decades, until 2009, when advanced age forced my grandmother to move out of the house she'd lived in since 1976. I unearthed a box full of family 8mm films at that time, and had them all professionally digitized in 2011. I had no idea my LEGO film was an unusually early example of the genre until I happened to read the Wikipedia page for brickfilms a few days ago, in anticipation of taking my little girl to see The LEGO Movie.
I've posted my film (and a few other 8mm animation experiments from the summers of 1979, 1980, and 1981) on YouTube.
The "LEGO City" footage was captured in our back yard at 5506 Mt. Vernon in Dallas on my mother's 8mm Kodak M12 Instamatic movie camera with no frame control. (I simply had to push and release the "record" button on the front as quickly as possible.) The camera had no sound capability. It was mounted on a tripod I saved up for and bought that summer at my local Target store.
That summer we lived in a ramshackle rent house with no grass in the back yard. (We only lived there for six months; in fact, the little house was torn down as soon as we left, and a brand new home was built on the lot in early 1980.) A yellow sheet spread out over the dirt served as the land, a blue blanket the sea. Every LEGO set I owned was assembled for the coastal "main street" scene depicted. The storyline features the sea rescue of a pilot (and the recovery of his seaplane), a female pedestrian being hit by a car (and the resulting attention of hospital and police personnel), and general agitation caused by construction vehicles at the nearby airport. The final few frames show that meanwhile, astronauts are enjoying exploring the moon.