Do you enjoy watching online videos that have comments from other viewers shooting across the screen? If not, you are probably too old.

But these so-called bullet-screen videos are becoming increasingly popular among young Internet users, making the sites red-hot investment targets.

AcFun, one of the most popular, announced on Thursday it had landed $60 million in backing from SB China Capital, a venture capital firm.

Founded in 2007 and one of the first in China to feature the bullet function, it boasts a strong portfolio of animation, comics and games video titles.

Liu Tianmin, a partner at SB China Capital, said that with a growing focus on younger audiences, he is confident the culture and entertainment industry will maintain its rapid growth for some years to come.

"Bullet-screen online video sites such as AcFun are attracting huge interest among younger viewers," he said, adding his company may well invest more in the site.

Industry commentators said the post-1990 generation is driving this booming sector, and expected investors to bet big on the continued success of sites like AcFun and their growing legions of young supporters.

Xue Yongfeng, an analyst with Analysys International, said that while viewers aged between 26 and 36 form the core of Internet users in China, the under-26s are expected to play a major role in shaping its future.

"That's why Internet giants Alibaba (Group Holding Ltd) and Tencent (Holdings Ltd) are so focused on investing in bullet-screen websites and technology," he said.

AcFun's latest $60 million funding comes just months after it raised $50 million from China's online video giant Youku Tudou Inc.

Both SB China Capital and Youku Tudou have strong connections with Alibaba.

Previous media reports have suggested Tencent may already have invested in Bilibili, AcFun's major rival, but both sides have refused to confirm it.

Bilibili focuses on animation, comics and gaming content featuring bullet-screen functions and is believed to have around 50 million users, most of which are under 24-years-old.