Since alot of fx are based off bluring these days I thought I'd show something I made in 2004 that shows how the base of blur fxing works. The code is rather old style but whatever it shows you the basic idea behind it.
[Script Info]
; This is a Sub Station Alpha v4 script.
; For Sub Station Alpha info and downloads,
; go to
http://www.eswat.demon.co.uk/
; or email
kotus@eswat.demon.co.uk
Title: Blur FX
Original Script: <unknown>
ScriptType: v4.00
Collisions: Normal
PlayResY: 768
PlayDepth: 24
Timer: 100.0000
[V4 Styles]
Format: Name, Fontname, Fontsize, PrimaryColour, SecondaryColour, TertiaryColour, BackColour, Bold, Italic, BorderStyle, Outline, Shadow, Alignment, MarginL, MarginR, MarginV, AlphaLevel, Encoding
Style: Default,Arial,48,16777215,65535,65535,16777215,0,0 ,1,3,0,5,30,30,30,0,0
[Events]
Format: Marked, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: Marked=0,0:00:04.00,0:00:05.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx180\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:04.00,0:00:05.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx220\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:06.00,0:00:07.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx180\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:06.00,0:00:07.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx220\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:05.00,0:00:06.00,*Default,,0000,0000 ,0000,,{\pos(483,375)\bord1\shad0\b1\fscy20\3a&H30 &\t(0,500,\1a&H60&\3a&H80&\fscy30\bord1)\t(500,800 ,\1a&H00&\3a&H00&)\t(600,1000,\fscy20)}\N{\fscy100 }MnT
Dialogue: Marked=0,0:00:05.00,0:00:06.00,*Default,,0000,0000 ,0000,,{\pos(483,375)\bord1\shad0\b1\fscy20\3a&H30 &\t(0,500,\1a&H60&\3a&H80&\fscy10\bord1)\t(500,800 ,\1a&H00&\3a&H00&)\t(600,1000,\fscy20)}\N{\fscy100 }MnT
Dialogue: Marked=0,0:00:07.00,0:00:08.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx180\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:07.00,0:00:08.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx220\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:09.00,0:00:10.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx180\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:09.00,0:00:10.00,*Default,,0000,0000 ,0000,,{\pos(460,380)\bord1\shad0\b1\fscx200\3a&H3 0&\t(0,500,\1a&H60&\3a&H80&\fscx220\bord1)\t(500,8 00,\1a&H00&\3a&H00&)\t(600,1000,\fscx200)}\h{\fscx 100}MnT
Dialogue: Marked=0,0:00:08.00,0:00:09.00,*Default,,0000,0000 ,0000,,{\pos(483,375)\bord1\shad0\b1\fscy20\3a&H30 &\t(0,500,\1a&H60&\3a&H80&\fscy30\bord1)\t(500,800 ,\1a&H00&\3a&H00&)\t(600,1000,\fscy20)}\N{\fscy100 }MnT
Dialogue: Marked=0,0:00:08.00,0:00:09.00,*Default,,0000,0000 ,0000,,{\pos(483,375)\bord1\shad0\b1\fscy20\3a&H30 &\t(0,500,\1a&H60&\3a&H80&\fscy10\bord1)\t(500,800 ,\1a&H00&\3a&H00&)\t(600,1000,\fscy20)}\N{\fscy100 }MnT