You're welcome.
The number is different because in that example you're averaging the last 32407 results, in the other example you're averaging the last 50 (selectable up to 1000).
Depending on how many results you're averaging the average can change.
Welcome Johndoe,
You're seeing the average speed for your provider, the Speed Index is the current average of all users on TestMy.net.
Here's what it looks like on my computer right now...
The Speed Index changes throughout the day because the average speed fluctuates.