UPDATE 6 Sept. 23: The designation list is here. TikTok is a social networking service; YouTube is the only designated video-sharing platform (as discussed below I think the arguments are equally strong either way for YT.)
Is TikTok providing an online social networking service (SNS) under the EU’s Digital Markets Act? I think it is closer to a “video-sharing platform service” than a SNS. It isn’t centred around users’ social graphs (its recommended videos can come from any other user, based on people’s profiled interests), although users can “follow” each other. However, when you look at the DMA’s SNS definition (Art. 2(7)):
a platform that enables end users to connect and communicate with each other, share content and discover other users and content across multiple devices and, in particular, via chats, posts, videos and recommendations
I think you could argue it is. Is B seeing a video from A a communication? (Must communication be bidirectional? I don’t think so. And B can “reply” to A’s video.) Is TikTok showing B a video from A the same as A “shar[ing] content” with B? TikTok’s recommendation algorithm would certainly count as a method for “discover[ing] other users and content”. And B can “connect” with A by following them, allowing A to “share content” with B. (For other non-TikTok users, I can recommend PocketLint’s explanation and this great Washington Post article!)
The DMA’s video-sharing platform (Art. 2(8)) definition points at the Audiovisual Media Services Directive Art. 1(1)(aa):
‘video-sharing platform service’ means a service as defined by Articles 56 and 57 of the Treaty on the Functioning of the European Union, where the principal purpose of the service or of a dissociable section thereof or an essential functionality of the service is devoted to providing programmes, user-generated videos, or both, to the general public, for which the video-sharing platform provider does not have editorial responsibility, in order to inform, entertain or educate, by means of electronic communications networks within the meaning of point (a) of Article 2 of Directive 2002/21/EC and the organisation of which is determined by the video-sharing platform provider, including by automatic means or algorithms in particular by displaying, tagging and sequencing;
The TFEU’s Arts. 56/57 define services, which must be “normally provided for remuneration”. The European Commission’s Guide to the case law of the European Court of Justice on Articles 56 et seq. TFEU specifies this includes cases where a party other than the user (eg an advertiser) is paying for a service, citing Case 352/85 Bond van Adverteerders and Others  ECR 2085, paragraph 16.
Given this, TikTok is clearly “devoted to providing… user-generated videos… to the general public… to inform, entertain or educate, by means of electronic communications networks”, determining the selection of videos “by automatic means or algorithms”.
Finally, can a single app provide more than one type of Core Platform Service (CPS) in DMA terms? iMessage is an app supporting two types of CPS: Number-Independent Interpersonal Communications Service or NIICS (blue bubbles) and Interpersonal Communications Service or ICS (green). The main Skype service is a NIICS; its bridging functionality to the telephone network is an ICS. So perhaps TikTok is providing both an SNS and a video-sharing service? Is it important to distinguish the elements? Twitter user @Gateklons commented:
We shall find out what the European Commission thinks in September, when it publishes its list of designated services! TikTok owner Bytedance has already told the Commission it meets the quantitative thresholds for designation as a gatekeeper ?
PS TikTok is joining Meta in adding a Twitter-like service (no ActivityPub support though ??). These services are so similar they would be a very easy first target for a DMA social networking service interoperability requirement, the need for which the European Commission must assess by 2026 ?
Would a TikTok-like service without any social functionality still be an SNS? (YouTube similarly allows users to follow each other, comment on videos, etc.) Does an interoperability requirement need to be extended to both types of core platform service? ?
PPS US Republicans aren’t completely insane to be thinking about what it means for a totalitarian regime ultimately to control “a platform that’s shaping how a whole ?? generation is learning to perceive the world.”
The EU’s Digital Services Act will in time tell us a lot more about TikTok’s algorithms, but will this ultimately become a serious matter of media plurality, at least in jurisdictions that care about such things (referenced by DSA Art. 34(1)(b))? And could interoperability help?
UPDATE: As required by the EU Digital Services Act (Art. 38), TikTok will allow EU residents to turn off their personalisation algorithm (more precisely, “provide at least one option for each of their recommender systems which is not based on profiling [as defined in GDPR Art. 4(4)]”):
This means their For You and LIVE feeds will instead show popular videos from both the places where they live and around the world, rather than recommending content to them based on their personal interests. Similarly, when using non-personalised search, they will see results made up of popular content from their region and in their preferred language. Their Following and Friends feeds will continue to show creators they follow, but in chronological order rather than based on the viewer’s profile.
This is DMA-nerd-tastic. Will different obligations video-sharing vs SNS) apply to the different feeds? ?