How much disk space does StreamAuthor 2.5 consume when recording a 1 hour audio and video file?

File sizes depend on the encoding profile you are using. For example, the 128 Kbps template uses 96 Kbps bandwidth.

Here's a sample formula:
96K / 8 (bit->Byte) x 60 (seconds) x 60 (minutes) = 43.2 MB (about 1/14 of a VCD with MPEG-1 format)