I think the trend has seemed nearer shopping patterns than affiliate ones in previous years but they seem to coincide if a4uforum traffic trend is similar to affiliate ones, but you could be right and I do not profess to know, yump.
Talk on CCT thread suggested shortages of leading toys on and offline. I would imagine suppliers would prioritise biggest customers as stocks came through, and I am guessing retailers would then prioritise offline sales since that gets customers into stores where they are more likely to make impulse purchases. Since you cannot accurately forecast the hottest toys months in advance when ordering stocks, I think the trend you point out of online shortages may recur each year for the best sellers.
Tesco has done well if the market update is correct although I thought they might have done better.
Tesco 409-3/4 up 7
Reports of strong Christmas trading, with internet sales seen up 30 pct