Facebook last week signed agreements with several content firms — among them Vox, Buzzfeed, ATTN and Group Nine Media, according to reports. The deals are widely viewed as part of the company’s strategy to attract millennials to its live-streaming Web content. Facebook will offer multi-tiered programming, according to a report that cited sources familiar with the plans. The service is expected to include Facebook’s own scripted original shows, which will run up to 30 minutes, as well other companies’ shorter videos, running up to 10 minutes.