How total data rate is calculated?

[Netozai]

How total data rate of a encoded video is calculated? Is it simply the sum of video and audio data rates?

For example, I encoded a video clip into Flash Video using On2 VP6 codec. Following is the encoding details for this Flash Video file reported by the MediaInfo software tool. As you can see, the total data rate is shown as 222 Kbps, where as the sum of video (150 Kpbs) and audio (32 Kbps) data rates is only 182 Kbps. Why is the difference - 222 Kbps vs 182 Kbps?

----Encoding Info of Flash Video File by MediaInfo Tool--------

General #0
Complete name : Video Clip.swf
Format : Flash Video
File size : 4.50 MiB
PlayTime : 2mn 50s
Bit rate : 222 Kbps

Video #0
Codec : On2 VP6
PlayTime : 2mn 50s
Bit rate : 150 Kbps
Width : 320 pixels
Height : 256 pixels
Aspect ratio : 5/4
Frame rate : 29.970 fps
Bits/(Pixel*Frame) : 0.061

Audio #0
Codec : MPEG-1 Audio Layer 3
Bit rate : 32 Kbps
Channel(s) : 1 channel
Sampling rate : 22 KHz
Resolution : 16 bits
Video0 delay : 75ms

-----End------

[Baldrick]

Doesn't a swf include some extra stuff like a player or something? That's maybe why MediaInfo thinks that the total rate is so much bigger.

http://en.allexperts.com/q/Shockwave-Flash-1515/FLV-vs-SWF.htm