It depends how long you need the Light for and how well regulated and life of battery needed.
This application for camera video ( short term) is suitable for short battery power. or flash. .
As LED quality on Ebay has no tolerant, expect wide variation and cheaper quality, more bluish colors on cool white etc.
That video uses much less than rated power which may be a good choice for you to regulate voltage for 10 second finger test.
Lipo pack is best to use for long term use such as those on cordless drill, unless you like to buy cheap alkaline by 100 pc qty.
It is better to define your acceptance criteria for the project in terms of;
- CCT colour, brightness in lumens ( to reflect light power) or mcd (to look at light ) , minimum battery time., control, stability of brightness
If you already have the LED strips of 5m length , each R in each series of 3 LEDs determines current rise above 2.6 past 3.1V per LED. This allows dim use from 9 V to full power at 14.2 on car ( for most!) or 12V nominal if specified as max.!