In a song, is しょう pronounced shouwo?

[teeny tiny boy]

君は忘れたのでしょう
Lyrics quoted from the song named Uso, here is the video:
[redacted by mod]

からくれないにそまるとげつきょう
Lyrics quoted from the song named 渡月橋 ～君想ふ～, here is the video:
[redacted by mod]

The last syllables しょう and きょう are pronounced as shou and kyou, the last alphabet u is the prolonged sound of the syllables, but when I hear the songs from Youtube, the singer seemed to pronounce the syllables as shouwo an kyouwo. Since they are from two different songs, so it is definitely not a coincidence, nor a mistakes. So when I sing the songs, what is the right way to pronounce the syllables?

 

[wind-sky-wind]

Singing is different from talking.
There is usually one syllable in one note when singing.
"しょう" or "きょう" is actually one syllable, but in this song,
there are two notes in "きょう."
So, she pronounces like kyou-wo in two syllables.

Similarly, in this song, in "だっ," which is usually one syllable, there are two notes.
So, she pronounces like da-a.

Note: I can't watch the first video here in Japan.
So, I just talked about the second one.

Edited: I searched and found another video.
In that song too, there are two notes in "しょう."
So, he pronounces like shou-wo in two syllables.

 

[frequency]

shou-wo

Maybe it sounds like that and the singer sings like that. As you and Wind said, the two are shō and kyō.
(Cross-post)

 

[Flaminius]

We call it epenthesis for a phoneme to be inserted in the middle of a word. Epenthesis of /w/ occurs frequently in speeches.
E.g., bawai for baai (Baai is a case or occurrence.)
Since I remember hearing announcers from NHK say it, I think it has insensibly established itself as a full member of phonetic family of the Japanese language. In other words, people don't care if you say baai or bawai. It does not change the meaning or the nuance of the word.

In fact, /w/ has been largely lost in Modern Japanese except in the word-initial position. Even for words for which the standard variety requires /w/ in the middle, you can hear /w/ dropped in casual or hurried speeches. Conversely, it can be inserted without changing the meaning of a word.

In case of bawai above, /w/ was attached to the second /a/ in order to separate it from the first. After all, the word is etymologically ba-ai.

In general, a long O is pronounced with the same pitch throughout. In sheet music, it is represented by a single note, typically with length twice as much as the short vowel. When a long vowel is assigned to two ascending notes, the second note is sung with more force than for the first. The /w/ is inserted as the result of effort applied.