I downloaded Lion Brand Jiffy Knit Dancing Star baby bunting pattern # 638. This is a super cute bunting in the shape of a star.

Right out the gate, I'm confused by a bolded sentence at the beginning of the instructions' Use a separate strand of yarn when casting on at beg of rows'
I don't understand- am I supposed to use a new ball of yarn for each row that instructs me to cast on some stitches at the beginning?
Starting the left leg, rows 3 and 5 cast on 2 st at beg. . The right leg casts on 2 st on rows 2 and 4 Why am I doing this? Thanks in advance for your help.

Link (http://www.lionbrand.com/patterns/638AD.html?noImages=) to pattern... I've seen this question before, and yes I think you're supposed to CO with a new end every time. Then the legs will get joined together.

Here's a link (http://www.knittinghelp.com/forum/showthread.php?t=103775) to the older discussion. I don't see why you need to use a new strand of yarn each time you cast on.
Also, (and this comes up later) I don't see any difference between casting on at the end of one row, then the beginning of the next as opposed to casting on the total number of sts at the beginning of the new row using the working yarn.

Right, I was going to add - you're 'supposed' to CO with new yarn, but I don't think it's necessary.

Using a knit CO is possibly a better choice, and it's done at the beg of a row. To CO at the end of a row you do a backward loop and that can get messy when there's more than 3 or so sts.

Thanks everyone for helping me out!