Yes it "plays" it, but the vast majority of the time is below 30FPS in the first video. And that was in pretty non-intense scenes. And what if they want to play split screen co-op, one of my favorite features of the lego games? I would be interested to see how the 5350 handles that.
And, yes, yes, I know a 7 year old is not going to run fraps to monitor the framerate. I do however, think he would notice the kind of stuttering and slowdown that were in the first part of the first video when the FPS was dropping into the teens and twenties. The point is not whether it is possible to play on the 5350, but whether it is the best choice. Personally I would go with the pentium, since the igp of the unlocked pentium (from the few benchmarks we have) appears faster than the 5350, and it would absolutely demolish it if later the OP decided to add a discrete card. But in the interest of trying not to inflame the intel vs amd debate, I still would suggest a more powerful FM2 APU.