So, according to my profile, I'm a "Top contributor (Games, Players)"

[zbinks]

I think you have to crack the Top 100 contributors list for the category in order to gain the Top Contributor achievement for the category.

• In order to contend for the Top 100 Blu-Ray Movies contributors you'd currently need to have over 14,000 accepted category submissions.
• In order to contend for the Top 100 DVD contributors you'd currently need to have over 12,000 accepted category submissions.
• In order to contend for the Top 100 Movies contributors you'd currently need to have over 1,500 accepted category submissions.

I think you still get to keep the achievement if you eventually fall out of the Top 100 list, though.