This year's winners in the student competition of the American Film Institute's Video Festival exhibit a certain basic competence but also a pitiful lack of daring. Three winning tapes will be shown tonight at 7 on Channel 26, and they do not send you away bubbling with enthusiasm.

Kenn Beckman does show some signs of life with his insouciant five-minute prank, "Song of the Street of the Singing Chicken," in which a bunch of hens and roosters and one cat toddle around a yard to the tune of an infectious chickenesque ditty by "Blue" Gene Tyranny. This is the kind of tape that, were it one minute longer, would drive one mad, but at its present length induces smiles.

The remainder of the program consists of two documentaries on suspiciously trendy topics: "Long Train Running," a report on the history and limited future of The Blues in Oakland, Calif.; and "Pregnant but Equal," a feminist dirge on "the fight for maternity benefits."

"Long Train," by Marion Riggs and Peter Webster, is nothing if not reverential toward The Blues, which are still sung in certain Oakland dives but which have a proud past. Performers like Sugar Pie DeSanto reminisce, Lowell Fulsom recalls how he used to put his hat on after grateful customers had filled it with money and a modern-day Blues singer offers an autobiographical refrain which begins, "I loved the woman / but she got cancer from smokin' cigarettes."

"Pregnant but Equal" traces progress made in obtaining rights for working expectant mothers and was made by Judith Pomer and the Women's Film Project in Cincinnati. The material may be of value, but the execution is doggedly routine and utilitarian. The half-hour tape has the tone and ambiance of something you'd expect to see at 6 a.m. on WCCP in Vladivostok.

This portion of the Video Festival appears an unqualified flop.