One thing to note about the AMD A9-9420, it uses the flawed AMD design of old where 2 execution units in a pod were refereed to as 2 cores. This CPU is actually a single pod with 2 execution units and 1 FPU. It is also using the quite old 28nm fabrication. Unless this was the cheapest laptop in the world, you can do better with an intel. A modern intel processor will give you atleast 2 REAL cores and a smaller fabrication producing less heat and using less power.
The design is no way flawed, it just isn't particularly modern. One module will provide two real cores. Two very limited cores... at least in current workloads. Also, the FPU in BD/PD is at least 1.75 and SR/XV is at least 1.5.
I only need a laptop for the basics such as watching HD videos, iTunes and browsing. Will this accomplish that task?
Yes, but not as well as something Intel or as cheap...
China-origin M3-7Y30s are good for sub-$500. Usually, are FHD(1920x1080), etc.
https://ark.intel.com/products/95449/Intel-Core-m3-7Y30-Processor-4M-Cache-2_60-GHz-
1 GHz to 2.6 GHz
4 MB L3 cache, AVX2(Full 256-bit capabilities), Speedshift, and 4.5W TDP. Supports QuickSync(KBLv) which has 10-bit VP9 support.
versus
A9-9420... 3 GHz to 3.6 GHz
1 MB L2 cache(No L3), AVX2(Half-rate 256-bit capabilities), no Speedshift, and 15W. Supports UVD/VCE which is not as good as QuickSync currently.
Ideally for the A9 part to become competitive to the m3, it would need at least to run at 5.2 GHz. Except, it will never beat the M3 with just that alone.
If you want a laptop that will do anything for at least 4 years... Kaby Lake-R is where it as at.
https://ark.intel.com/products/124967/Intel-Core-i5-8250U-Processor-6M-Cache-up-to-3_40-GHz
Get something between the $599~$699 mark with a 1080p screen you are good.