A common fashion is to add animations and noises as overlays. These can look cute and sometimes be appropriate to bring one's attention at a non-obvious item at the right time. On the other hand, abusing them has implications like distracting from the topic or aggressing the listener with sudden sounds at an improper level versus the speech level. Extremes in volume should be avoided. Especially on large screens, gadgets which move all around will require the listener's eyes to keep moving for no benefit. If these gadgets are large or move fast, this may also cause constant visual contrast extremes or migranes to people who are prone to those, who are then likely to close their eyes for the rest of the presentation.
New narrators are nervous and prone to speak fast while not breathing properly. Some vloggers also accelerate their video at the editing phase and strip all pauses including breathing.
On the other hand, professional oratory skills take in consideration aspects such as pace, tone, emphasis cues and pauses, strategic breathing pauses to let the audience think, gestures, visual communication, body language, etc. It is normal for the average vlogger to not have received oratory skills training and for some to believe that they should simply mimick common popular styles, or feel that they should fit as many words as possible in the shortest time. But being aware of this is the first step to begin to assess one's skills and improve them.
A constant sustained pace bores the audience in a very short time. An uncontrolled pace reduces communication effectiveness. These are like the paragraphs of a text. Other oratory skills include using devices like humor, metaphores, strategic pauses, etc. There are courses and books dedicated to the topic. It is also a good idea to study what makes your favorite prophessor so attractive to listen to for hours.
Showing written text while narrating different words forces the audience to either read and stop listening, listen and ignore the words, or to catch and miss a little of both. If showing words, with exceptions it is best to simply read them before proceeding to another sentence. It is also important to show any text long enough to allow readers of various paces to read them. The reading pace of a person also naturally varies with factors such as light, screen size, font size (too large is not always better), comfort and environmental distractions. Adding distractions as a result of presentation misdesign is best avoided. A good technique is to have the equivalent of a board where text can remain a while, like is used for teaching. Animated text that is moving or dancing is also not recommended, where it may simply become a distraction, the first topic of this short text.