Pre roll video inventory (video streams preceded by ad units) has grown an average of 105.2% annually over the past five years, compared to free or ad supported content streams, which averaged 72.3%, AccuStream says. Usage patterns in Q1 2006 reveal an average of 1.2 bln free or ad supported streams served by major media brands per month, and 94% of those streams have pre roll inventory. The report aggregates branded sites together to create total pre roll share. Yahoo controlled 23.97% of pre roll video streams from January through April 2006; TimeWarner followed with 13.7%. Microsoft had 11.40%, Viacom with 8.54%. Non affiliated, independent or other branded sites combined to control 27.16% of total ad supported or free streams.