It appears that 1500k is the default max file upload in WPMU, or that the admin team has initially set this very, very low limit. Even a 5 minute mp3 audio podcast won’t fit in the limits.
I did notice that one “error” indicated that 50M was the limit, which seems quite reasonable. But 1500k just won’t work if we imagine students posting audio and video clips they produce, extended powerpoints, even high quality images or PDFs. It may be that there are a
Obviously, remote hosting of the media is possible. And there’s a value in learning to bring together in one place media housed at various locations in the cloud. But it seems a bit more cumbersome than necessary in an environment where a terabyte of hard drive space runs about $100, and less in bulk.