Sandy,
dunno leh, when I did my own testing of uploading an attachment here, I have to click the Post button first before I get to see the Browse button to select the file.
another way is to use those photo/video hosting website, upload your file there and then paste the link here.
most of these website would require you to sign up (free) as a member.
this tinypic website does not require you to sign up though, simply upload and share the link.
http://tinypic.com/
here's their FAQ:
<blockquote><hr size=0><!-quote-!><font size=1>
quote:</font>
Image files cannot be larger than 1600 pixels (either width or height). Images that are too large are resized to the largest acceptable size.
Acceptable Images types are: jpg, png, gif, base 64 encoded image, or bmp.
Video files cannot be larger than 100 Megabytes or longer than 5 minutes. If you upload a video longer than 5 minutes it will be truncated to 5 minutes.
Acceptable video types are: 3g2, 3gp, 3gp2, 3gpp, 3p, asf, avi, divx, dv, dvx, flv, moov, mov, mp4, mpeg4, mpg4, mpe, mpeg, mpg, qt, wmv, xvid, rm <!-/quote-!><hr size=0></blockquote>
I've not use this tinypic before, just saw people using it and sharing the info for your consideration ya.