You probably work in a resolution of 800x600 on your computer.
Video can only display about 525 lines of information vertically.
So, some of the resolution you see on your computer monitor will
be lost in the transfer. In photographs, because of the color and
abundance of detail, your eye usually can't tell the difference.
But with type, especially if the font has serifs -- those little
curlicues at the ends of letters -- enough is lost in the video
transfer that small font sizes don't show up very well. Usually
sizes larger than 14 point look o.k., and the "sans serif"
fonts work better than those with serifs.