In the video Valerie combines the chain block both with a small panel and with a large square of feature fabric. Either way you need to create the chain block first and then make the panel/feature fabric to the same size. This avoids funny and awkward sizes of strips.
You need to start by knowing approximately how big the block needs to be, how many of these blocks you need to make and then working out how many logs you need around the starting point. Starting point is a 9 patch.
In the video there are 5 chain blocks, so that they run from each corner and one in the centre, teamed up with 4 panels and/or feature fabric squares.

Click here for Workshop Notes
Click here to learn more about Valerie Nesbitt.
Click here to watch the full length version of this Taster