To expand on this:
It is only currently possible for games that have been completed -- one cannot replay a game in progress (that I am aware of).
To do it, find the table number of a completed game (or the link to it). This can easily be found for your recent games by going to one's profile, and in the bottom left, looking at the section labeled "Latest results:". Click on one of the game names to go to the table. Then, click the button "Replay Game." This will then allow you to choose any player in the game and see the game from their perspective. An unfortunate side effect of this is that if they played in a different language, you will see the results in a different language. But, you will still be able to see all the cards, die rolls, etc., as if you were them. You can then proceed through the game at your own pace, either by advancing one move at a time, or advancing quickly to a particular move (including the end). Knowing
why a particular move was made, though, is not always clear.
Another way to learn, too, is to go to tables that are being created, and ask if you can ask questions during game play. Anybody can be at an active table (whether they are playing or not), and be part of the conversation. Etiquette does request that you ask permission first, though, as some moves cannot be explained without giving away information that should only be known to the player. But, I've run across many people more than willing to answer questions about the mechanics of a game during play. Strategy is a different matter... (Generally they don't want to reveal their strategy to an opponent.)