For those that prefers to read, you can find the transcript of the video below.
Amber is the soft currency of Predecessor which means its the currency you can earn by simply engaging with the game. Currently you can earn it in two different ways, as a reward at the end of each match you play and also when you level up your account. On the level up part you gain a bigger chunk of Amber every 4 levels.
Amber is used for unlocking new heroes, Omeda announced that it will be used for other things in the future as well but no details for now. To unlock a hero, you can either go to their page and click the unlock button or do it inside the shop.
One very important thing to know about the hero unlocking is that not all heroes have the same amber cost. Indeed based on the ease of play and their time of release hero are placed in 5 different tier with different cost. Here is the whole table of the released heroes as of the 0.16 patch release (which is the patch of the free to play release).
I would recommend to start unlocking the cheaper one first since it will give you the fastest amount of heroes in the shortest amount of time. Moreover Tier 1 and 2 heroes are pretty straightforward to pick up and play which are perfect if you are discovering the game.
As a last note we can notice that there is a Tier 5+ in the table which is the cost of a new hero for their first week of release. If you want to play it on day 1 you will have to get out the big bucks but after a week it will be down to the price of a Tier 5 so if you are ready to wait a little bit the price will drop down.