Scholars have long delved into the realm of MOOCs. However, with the proliferation of diverse platforms hosting course videos, it was realized that learning experiences may vary across these platforms. Hence, this research explores the forums within two distinct online learning platforms: the formal MOOC and the informal video-sharing platform. According to self-determination theory, it is assumed that different motivations influence the behavior of learners on different platforms. Through the content analysis and social network analysis, the research reveals that learners' performance on formal platforms tend to exhibit centralization, with they primarily focused on course. In contrast, performance on the informal platform displays a decentralizing trend, emphasizing knowledge transfer and mutual encouragement. The variances in knowledge production behaviors among these learners should be duly acknowledged. For future development of online learning platforms, the characteristics of content and learner behavior in informal forums require attention and integration.