You know, I wouldn't think these bonus discs would spoil later seasons.

Lost is a show squarely set in the DVD era, and the seasons were released each year right before the start of a new season (for example, S1 was released a couple weeks before S2 started, and so on down the line).

I don't think the producers would risk spoiling the next season for some DVD bonus features most people wouldn't watch in the first place, plus, the bonus features were probably produced at the same time as the episodes, so it isn't like the Producers had the luxury of looking back on everything they had ever done with the show during the making of the bonus features. They might spoil the season if you watch the bonus material first for some odd reason, but I can't see 'em spoiling the whole show.

But, I don't watch the show, and don't plan to, so I can't tell you about the DVDs... just what seems most logical.